Unit 1 Topic 1 Packet

Summary

This lesson provides an introduction to the structure of water and hydrogen bonding, starting with a chemistry review of matter, elements, compounds, and the periodic table. It covers atomic structure, the Bohr and Lewis dot models, and the types of chemical bonds, including covalent, ionic, and hydrogen bonds. The video emphasizes water's unique properties such as cohesion, adhesion, high specific heat, evaporative cooling, and its role as a versatile solvent. Additionally, the lesson highlights how water's structure supports life, especially in plants and marine environments.

Takeaways

• 💧 Matter includes anything that takes up space and has mass, such as liquids, solids, and gases.
• 🧪 An element cannot be broken down into another substance by chemical reactions, while a compound consists of two or more elements combined in a fixed ratio.
• ⚛️ Essential elements like carbon, hydrogen, oxygen, phosphorus, and nitrogen (CHOPIN) make up 96% of living matter, while trace elements are required in small amounts.
• 🔢 The periodic table is organized by groups (vertical columns) that have the same number of valence electrons and periods (horizontal rows) with the same number of electron shells.
• 🔬 The Bohr model shows electrons orbiting the nucleus in energy levels, while the Lewis dot model focuses only on valence electrons.
• 🔗 Chemical bonds form based on the octet rule, where elements gain, lose, or share electrons to complete their valence shells, leading to stability.
• 🧲 Covalent bonds involve the sharing of electrons between atoms, which can be polar (unequal sharing) or non-polar (equal sharing).
• ⚡ Ionic bonds are formed by the transfer of electrons between oppositely charged ions, typically between metals and non-metals.
• 🌊 Hydrogen bonds are intermolecular attractions, not actual bonds, occurring between polar covalent molecules like water.
• 🌡️ Water has unique properties due to hydrogen bonding, including cohesion, adhesion, capillary action, temperature control, and solvent capabilities.

Q & A

What is the difference between matter, elements, and compounds?

Matter is anything that takes up space and has mass, such as liquids, solids, gases, or living organisms. An element is a substance that cannot be broken down into simpler substances by chemical reactions, while a compound consists of two or more elements combined in a fixed ratio, like water (H2O) or sodium chloride (NaCl).

What are essential elements, and why are they important?

Essential elements, such as carbon, hydrogen, oxygen, phosphorus, and nitrogen (abbreviated as 'CHOPN'), make up 96% of living matter. These elements are crucial for various biological processes, like forming biomolecules (proteins, lipids, DNA).

What are trace elements, and what role do they play in organisms?

Trace elements are required by organisms in very small quantities. Examples include iron (important for oxygen transport in blood) and iodine (needed for thyroid hormone production). Despite their small presence, they are vital for maintaining healthy biological functions.

How do you interpret the atomic number and atomic mass of an element?

The atomic number represents the number of protons in an atom, while the atomic mass is the combined total of protons and neutrons, averaged across all isotopes of the element.

What is the difference between covalent, polar covalent, and ionic bonds?

Covalent bonds involve the sharing of electrons between two non-metals. Polar covalent bonds are a type of covalent bond where electrons are shared unequally, leading to partial charges (e.g., in water). Ionic bonds occur when one atom transfers electrons to another, typically between a metal and non-metal, resulting in oppositely charged ions (e.g., sodium chloride).

What is the octet rule, and how does it relate to chemical bonding?

The octet rule states that atoms tend to gain, lose, or share electrons to complete their valence shell with eight electrons, resembling the stable configuration of noble gases. This rule drives the formation of chemical bonds between atoms.

What are hydrogen bonds, and how do they differ from other types of bonds?

Hydrogen bonds are weak attractions between a partially positive hydrogen atom in one polar covalent molecule and an electronegative atom (like oxygen or nitrogen) in another polar covalent molecule. Unlike covalent and ionic bonds, hydrogen bonds are intermolecular attractions, not true bonds.

Why is water considered a polar molecule, and how does this contribute to hydrogen bonding?

Water is polar because of the unequal sharing of electrons between oxygen and hydrogen atoms, with oxygen having a partial negative charge and hydrogen having a partial positive charge. This polarity allows water molecules to form hydrogen bonds with each other, contributing to water's unique properties.

What are cohesion and adhesion, and how do they contribute to water's movement in plants?

Cohesion refers to water molecules sticking to each other due to hydrogen bonding, while adhesion refers to water molecules sticking to other surfaces, like plant cell walls. Together, these properties facilitate capillary action, allowing water to move against gravity in plants from roots to leaves.

How do hydrogen bonds contribute to water's high specific heat and evaporative cooling?

Hydrogen bonds in water require heat to be absorbed to break and release heat when they form, stabilizing water's temperature (high specific heat). During evaporative cooling, water molecules with the highest kinetic energy leave as gas, cooling the surface they evaporate from, like during sweating or transpiration in plants.

Outlines

00:00

🔬 Introduction to Chemistry: Matter, Elements, and Compounds

The first paragraph introduces the concepts of matter, elements, and compounds. Matter is defined as anything that takes up space and has mass. Elements are substances that cannot be broken down by chemical reactions, while compounds consist of two or more elements in a fixed ratio, like water (H2O) and sodium chloride (NaCl). Essential elements such as carbon, hydrogen, oxygen, phosphorus, and nitrogen (CHOPN) make up 96% of living matter, while trace elements are needed in small quantities. The paragraph ends with a quick exercise, asking learners to review the role of essential and trace elements in the body.

05:03

🧬 Reading the Periodic Table: Groups, Periods, and Atomic Structure

This section explains how to read the periodic table. The atomic number represents the number of protons, while the atomic mass is the number of protons plus neutrons. Elements in the same group (vertical column) have the same number of valence electrons, important for chemical bonding. The horizontal rows, or periods, represent the number of electron shells. Valence electrons are explained in detail, and the paragraph reviews how elements are grouped in the periodic table based on these properties.

10:04

🔄 Bohr Model and Lewis Dot Model

This part introduces the Bohr model and Lewis dot model. The Bohr model shows electrons orbiting the nucleus in defined energy levels (shells), with specific electron capacities per shell. An example using lithium is provided, demonstrating its electron configuration. The Lewis dot model simplifies the Bohr model by showing only valence electrons around the element symbol. Both models are important for understanding electron arrangements and bonding.

15:04

💡 Chemical Bonding: Octet Rule and Covalent Bonds

The paragraph explains why elements form bonds based on the octet rule, which states that atoms will gain, lose, or share electrons to fill their valence shell. Covalent bonds are introduced as bonds formed by sharing electrons between two non-metals. These can be single, double, or triple bonds, depending on the number of shared electron pairs. The paragraph distinguishes between non-polar covalent bonds, where electrons are shared equally, and polar covalent bonds, where electrons are unequally shared, like in water (H2O).

20:05

⚛️ Ionic and Hydrogen Bonds

Ionic bonds are introduced as bonds formed through the transfer of electrons between atoms, usually between metals and non-metals, leading to the creation of oppositely charged ions (cations and anions). An example of sodium chloride (NaCl) demonstrates this process. The paragraph also explains hydrogen bonds as attractions between partially positive hydrogen atoms and electronegative atoms (like oxygen or nitrogen) in polar molecules, clarifying that these are attractions rather than actual bonds.

💧 Hydrogen Bonding in Water and Its Properties

This section dives deeper into hydrogen bonding in water molecules. It explains how hydrogen bonds cause water molecules to be attracted to each other, contributing to water's unique properties. Water molecules are constantly moving, with hydrogen bonds forming and breaking frequently, which gives water its structured nature. The paragraph emphasizes that hydrogen bonds occur between different water molecules and are responsible for water's liquid structure.

🌊 Water Properties: Polarity and Cohesion

The paragraph outlines key properties of water, starting with polarity. Water is a polar molecule, meaning it has unequal sharing of electrons, leading to hydrogen bonding. Cohesion is the attraction between water molecules, which is vital for the movement of water and nutrients in plants. The hydrogen bonds between water molecules are responsible for cohesion and surface tension, allowing water to resist external forces.

🪶 Adhesion and Capillary Action

This section discusses adhesion, the attraction between water molecules and different substances. Adhesion, along with cohesion, enables water to travel upwards through plant tissue, specifically the xylem. This movement is known as capillary action, a process where water climbs against gravity due to a combination of cohesion, adhesion, and surface tension, which is critical for nutrient and water transport in plants.

🔥 Water’s Role in Temperature Regulation

Water has a high specific heat, meaning it can absorb and release large amounts of heat without drastically changing temperature. This property helps regulate air and ocean temperatures and maintain stable conditions for marine life. Additionally, evaporative cooling—when water molecules with the highest kinetic energy leave as gas—helps prevent overheating in organisms and plants through processes like sweating and transpiration.

❄️ Ice Formation and Density

The paragraph explains how water's density changes when it freezes. As water cools, hydrogen bonds slow down, locking water molecules into a crystalline structure, which causes ice to expand and become less dense than liquid water. This property allows ice to float, creating an insulating layer that enables marine life to survive in freezing environments.

💧 Water as a Universal Solvent

The final paragraph highlights water's ability to dissolve many substances due to its polar nature, earning it the title of 'universal solvent.' Water molecules are attracted to ions and other polar molecules, forming hydrogen bonds that break apart solutes like sugars and salts. The process of dissolving ionic compounds is demonstrated using sodium chloride as an example, showing how water molecules separate ions into solution.

Keywords

💡Matter

Matter is anything that takes up space and has mass. In the video, matter is introduced as the basic substance of the universe, encompassing liquids, solids, gases, and even living beings like humans. Understanding matter is crucial for studying chemistry and biology, as it forms the basis of all physical substances, including elements and compounds discussed later.

💡Element

An element is a pure substance that cannot be broken down into another substance by chemical reactions. The video mentions the periodic table, which lists all natural elements, such as oxygen and carbon. Elements are fundamental to the study of chemistry and biology as they form the building blocks of compounds and are necessary for life's essential processes.

💡Compound

A compound is a substance composed of two or more elements combined in a fixed ratio. The video gives examples like water (H2O) and sodium chloride (NaCl). Compounds are vital in biological systems, where various elements combine to form molecules necessary for life, highlighting the importance of chemical bonding and molecular interactions in biology.

💡Essential Elements

Essential elements are those required for an organism's survival, including carbon, hydrogen, oxygen, phosphorus, and nitrogen (CHOPN), which make up 96% of living matter. The video emphasizes their role in biological processes, urging viewers to explore each element's function in the body. Understanding these elements is crucial in biology as they form the foundation of organic molecules like DNA and proteins.

💡Atomic Structure

Atomic structure refers to the arrangement of protons, neutrons, and electrons in an atom. The video explains concepts like atomic number and atomic mass, highlighting how electrons orbit the nucleus and how this structure is represented on the periodic table. Knowledge of atomic structure is essential to understanding chemical bonding, reactions, and the properties of elements and compounds.

💡Bohr Model

The Bohr model illustrates electrons orbiting the nucleus in defined energy levels or shells. The video uses lithium as an example, showing how electrons fill the first and second shells. This model is fundamental to understanding how elements form bonds and interact with one another, which is a core concept in both chemistry and biology.

💡Covalent Bonds

Covalent bonds occur when two or more atoms share electrons, usually between non-metals. The video discusses types of covalent bonds, such as single, double, and triple bonds, and differentiates between polar and non-polar bonds. These bonds are crucial for the formation of molecules like water, which exhibit specific properties essential to biological processes.

💡Ionic Bonds

Ionic bonds are formed through the transfer of electrons between a metal and a non-metal, resulting in the attraction between oppositely charged ions. The video uses sodium chloride (NaCl) as an example. Ionic bonds create ionic compounds and salts, which play critical roles in biological functions such as nerve transmission and muscle contraction.

💡Hydrogen Bonding

Hydrogen bonding is the attraction between a partially positive hydrogen atom in one polar molecule and an electronegative atom (like oxygen) in another. Although termed a 'bond,' it is more of an intermolecular attraction. The video describes how this bonding in water molecules leads to unique properties like cohesion and surface tension, influencing various biological processes, including the transport of water in plants.

💡Properties of Water

Water has unique properties like cohesion, adhesion, high specific heat, evaporative cooling, and solvent capabilities due to its polar nature and hydrogen bonding. The video discusses how these properties support life, such as cohesion allowing water transport in plants and water's high specific heat helping stabilize climate. Understanding these properties is fundamental in biology, where water's behavior affects all living organisms.

Highlights

Introduction to the structure of water and hydrogen bonding.

Review of chemistry concepts: matter, elements, and compounds.

Essential elements for life: Carbon, Hydrogen, Oxygen, Phosphorus, Nitrogen (CHOPN), making up 96% of living matter.

Explanation of trace elements and their importance in small quantities for organisms.

Overview of the periodic table: atomic number, atomic mass, groups, and periods.

Bohr model of an atom: electrons orbit the nucleus in specific shells, with examples like lithium.

Lewis dot model: Simplified Bohr model focusing on valence electrons around the element symbol.

Formation of chemical bonds based on the octet rule: elements gain, lose, or share electrons to complete their valence shells.

Types of bonds: Covalent (polar and non-polar), Ionic, and Hydrogen bonds.

Explanation of electronegativity and its role in bond formation, with fluorine being the most electronegative element.

Hydrogen bonding between water molecules and its role in water's unique properties.

Cohesion and adhesion in water, allowing for capillary action in plants.

Temperature control in water: high specific heat helps moderate air temperature and stabilizes marine life environments.

Ice density: water becomes less dense when frozen, forming a crystalline structure, allowing marine life to survive under ice.

Water as a universal solvent: able to dissolve ions and polar molecules due to hydrogen bonds.

Transcripts

welcome to unit one topic one today

we're going to be discussing the

structure of water and hydrogen bonding

but let's go ahead and get started first

with a quick review on chemistry

and let's start with what's the

difference between matter elements and

compounds so firstly matter remember

this is anything that takes up space and

has

mass so liquid solids gases you and i

rocks metals right all that that's all

matter

an element is something that cannot be

broken down

into another substance by chemical

reactions so think the periodic table of

elements right we have

lots of elements that occur in nature

and they can't be broken down into

another substance

compounds on the other hand are a

substance consisting of two or more

elements combined in a fixed ratio so

like

water h2o sodium chloride nacl

that's an example of a compound now

of all of our elements we have certain

ones that are considered essential

these are carbon hydrogen oxygen

phosphorus and nitrogen

or you can say chop it these make up 96

of living matter and then off of

essential elements we have things called

trace elements and these

are required by organisms but in very

small

quantities

so let's go ahead and take a minute i

want you to look up what are some

essential elements

why are they essential we went through

choppin so why don't you take

a second look at what each of those or

what role each of those plays in the

body

and then look up trace elements and try

to find some trace elements and what

what are

their roles in the body as well maybe

one to two trace elements

all right let's do a quick chemistry or

let's continue with our quick chemistry

review

i'm looking at this we this is our

element symbol here then we have the

atomic number

and then our atomic mass this is the

number of protons

plus neutrons averaged over all of our

isotopes so

looking at each element on the periodic

table

that's how to read this now going off of

this let's look at our groups and

periods so

groups elements in the same vertical

column

or in the same group have the same

number of valence electrons

now for the ap biology exam you only

need to know groups 1

2 and then we skip over 13 through 18.

and remember valence electrons this has

one two

and then we go to 13 for three four five

six seven eight and these are

noble gases here in group 18.

okay and then period this is going to be

the horizontal row um and anything in a

horizontal row will have the same number

of electron

shells okay what else do you remember

about the periodic table go and go ahead

take a minute think about

what you've learned in a previous

bio or chem class what do you remember

about the periodic table

okay let's go ahead and look at the bohr

model bohr models show electrons

orbiting the nucleus of an atom

and electrons will be placed on shells

around the nucleus

and remember each shell is a different

energy level and can hold up to a

certain number of electrons

first shell can hold two electrons

second shell

eight and third shell is 18 but for the

ap bio exam

we're not going to look at anything in

the third shell that can hold

more than eight electrons

all right so let's go ahead and look at

an example of a bohr model using

lithium so here's lithium on the

periodic table we can see it's in group

one period two um period two would mean

it has two

shells then group one means we have one

valence electron

i has three protons three electrons

um so how would we draw this well we

would put these shells or two shells

around the nucleus

the first shell remember can hold up to

two second shell can hold up to eight

but we would only have one left over so

we put that uh

final one on the second shell or our

valence electron our one valence

electron goes on that outermost shell

all right next let's look at our lewis

dot model a lewis dot model is a

simplified board diagram

it does not show energy levels it only

shows electrons in the valence shell or

the outermost shell

electrons are simply placed around the

element symbol and then we'll look at

lithium again in just a second

all right so lithium same thing as

before um so we would draw our element

symbol and then we would just draw our

valence electron in this case we have

one

so there we go there's our element

symbol and we drew the one

valence electron usually you start at

the top and then work your way

around clockwise so we start with the

first one at the very top and we only

have one

so we finish there

all right go ahead take a minute to

practice by going through the chart

in your packet

all right next let's go through the type

of types of bonds that we have

so elements want to be stable and

because they want to be stable they're

going to

go through the formation of chemical

bonds with other

elements and this is based upon the

octet rule

so it says that elements will gain lose

or share electrons to complete their

valence shell

and become stable like our noble gases

down at the bottom we have co2 and we

can see that

carbon and two oxygens are sharing

electrons

so that they become stable

now going off of the formation of bonds

chemical bonds this is based off of an

attraction between

two atoms resulting from the sharing or

transferring of valence electrons and

how are atoms attracted well it has to

do with their electronegativity which is

a measure of an atom's ability to

attract electrons to itself

so when you look at the periodic table

electronegativity

increases going to the right and going

up

so as you go to the right and up you

have these

most electronegative elements which

would mean

fluorine right here that's going to be

our most electronegative element on the

periodic table

all right so what types of bonds do we

have well firstly we have covalent bonds

and this is when you have two or more

atoms sharing electrons and it's usually

between

two non-metals these will form molecules

and compounds

and it can form up to three bonds a

single bond is

one uh pair of shared electrons

double bond is two pairs of shared

electrons

and then a triple bond is three pairs of

shared

electrons

now there are two types of covalent

bonds we have nonpolar

and polar non-polar covalent bonds is

when you have electrons sharing

being shared equally between two atoms

so for example

two oxygen atoms so here we have the

lewis dot structure for two

oxygens well what's going to happen

we'll see these unpaired electrons

they're going to now be shared equally

between our two

oxygen and so we can now see that that

formed a double bond

because we have two pairs of shared

electrons

all right next we have the polar

covalent bond this is when electrons are

not shared equally between the two atoms

so a good example is water

so here we have oxygen bonded to two

hydrogen because oxygen is more

electronegative it's going to be pulling

on the hydrogen

or pulling on the electrons more which

is why it has a partial

negative charge the hydrogen since

they're less electronegative are going

to have a partial

positive charge

and again this is due to that unequal

sharing of electrons

between our elements

all right next we have ionic bonds this

is the attraction between

oppositely charged atoms or ions and

it's usually between a metal and a

non-metal and it's when a metal

transfers electrons to

the non-metal this is going to form

ionic compounds

and salts a good example

is nacl or sodium chloride or lithium

fluoride now like i said this occurs

when there's a transfer

of electrons so there's a transfer of

electrons from one atom to another atom

forming our ions we have two types of

ions we have a cation which is a

positively charged ion and then an anion

which is a negatively charged ion

and here's an example of sodium chloride

so we can see

that sodium is going to transfer its

electron to chlorine

so it gives up its electron so it's now

n a

plus because it gave up an electron and

then chlorine gained an electron so it's

minus negative

all right and then lastly we have

hydrogen bonds

hydrogen bonds occur when the partially

positive hydrogen

atom in one polar covalent molecule will

be attracted to

an electronegative atom in another polar

covalent molecule

and this even though it's called a bond

isn't actually a bond

it's really an attraction and so it's an

intermolecular think

attraction that forms between molecules

even though it's called a

bond all right so why does this happen

well when a hydrogen atom is bonded to

an electronegative atom think like

oxygen

nitrogen fluorine those really

electronegative atoms

the electrons will not be shared equally

like we saw

in the example of water previously and

remember this is a polar covalent bond

right so we have this unequal sharing of

electrons

so this will cause hydrogen to have a

partial positive charge

and then the electronegative atom will

have a partial

negative charge just like we saw in

water

so let's look at water one more time to

see how these polar covalent bonds will

contribute to hydrogen bonding

all right so we can see that the solid

black lines here these are our polar

covalent bonds

and because we have these partial

positive charges

water molecules would be attracted to

each other so

here for example i'm going to look right

here so here we have one

partial positive hydrogen and we can see

that it's being attractive to the

partial negative oxygen

of another water molecule so again

hydrogen bonding is intermolecular

bonding

between molecules so in the water

molecule itself

so if we were to look at one water

molecule itself

let's say just this right here there's

no hydrogen bonding right we're looking

at polar covalent bonds

but then when you have multiple water

molecules coming together

that's where we see that attraction and

again that attraction

comes from these partial charges due to

the polar covalent bonds

so the partial char positive hydrogen of

one molecule

will be attracted to the partial

negative charge of

another molecule

now one thing to note about water is

that water molecules move a lot

hydrogen bonds form break and reform

with great frequency

and the hydrogen bonds between water is

what makes water more structured than

most

liquids right so let's go ahead

and look at the properties of water now

all right so here's a little overview of

the properties of water we have seven

properties that we're going to cover you

don't need to write this

but let's go ahead and look at polarity

first so this is something that we

already touched on so

again water is a polar molecule we have

unequal sharing of electrons and that's

what makes water

polar and that's also going to

contribute to the intermolecular

hydrogen bonds that form between water

molecules

all right our next property is cohesion

this is an attraction of molecules for

molecules of the same

kind i like to think cooperate

co-cooperate you cooperate

with other people water is cooperating

with other

water molecules why does this happen

well

the hydrogen bonds hydrogen bonds

between water molecules hold them

together

and increase cohesive forces

this is going to be what actually allows

for the transport of water and nutrients

against

gravity in plants it's also going to be

partially responsible for surface

tension which is a property of water

allowing

water to resist external force it's a

property

we see in things besides water too but

in this case we're just focusing on

water

all right and there you go there's

cohesion in that picture there we can

see that hydrogen bond or the dashed

line

between our water molecules causing them

to stick together

all right the next property of water is

adhesion i want you to think add we're

adding something else now so now this is

a cleaning of

one molecule to a different molecule

because we're adding a different

molecule now

this is still due to the polarity of

water but now it's going to be

causing it to be attracted to to

something besides water

now in plants this allows water to cling

to cell walls or in this case

to the xylem which is plant tissue it's

going to allow it to move

still against gravity and it can also

allow it to cling to cell walls

to travel up from root to leaves

all right and there we go there's those

hydrogen bonds forming between

water and the xylem in this case

all right here's a nice image to show

adhesion cohesion together

so again cohesion is water to water

which we can see right here

and then adhesion there's our our water

molecule sticking to

the xylem and each of these together is

going to be

partially contributing to that upward

flow of water through

the xylem now something else that's

going to

also allow for that upward movement of

water through the xylem is capillary

action

so when we have capillary action it's

actually

sort of a combination of forces so it's

cohesion adhesion surface tension all

sort of working together

to create this upward movement now

specifically this will occur when

adhesion is

greater than cohesion so water is more

attracted to the xylem

than it is to other water molecules

this is important for a transport of

water and nutrients in plants

because this is how water is going to

move upwards specifically from

roots to leaves and plants

all right next we have temperature

control firstly high specific heat so

water

can resist changes in temperature

because of hydrogen

bonds in order to break hydrogen bonds

heat has to be absorbed but then when

hydrogen bonds

form heat is released and this almost

stabilizes

the temperature of water so it really

resists changes in temperatures because

of these hydrogen bonds

and how they have to absorb but then

also release

heat now why is

a high specific heat important well it's

going to help mod

moderate air temperature so for example

large bodies of water

they absorb heat in the daytime but then

they release heat

at night it's also going to stabilize

ocean temperature which will benefit

marine life and then organisms can

resist changes in their own internal

temperature because we're

primarily made of water

all right next we have evaporative

cooling water has a very high heat of

vaporization

what that means is that molecules at the

surface

water molecules at the surface with the

highest kinetic energy

can leave as gas all right why is that

important in nature well

it's going to help moderate climate it's

going to stabilize temperatures

in lakes and ponds and then

animals and you know including humans

it's going to prevent us from

overheating right sweat which is

primarily water goes to the surface of

our skin

and those water molecules at the surface

with the highest kinetic energy will

leave as gas and when they do

we get that cooling sensation but it's

also important for

plants it's going to prevent leaves from

being becoming too warm in the sun

and this process is called transpiration

all right and then next we have density

or floating ice

and we know that when ice forms

as or as water solidifies it expands and

it becomes

less dense than liquid water again

everything is due to these hydrogen

bonds

so when cool water molecules move too

slowly

to break these hydrogen bonds remember

earlier i said these hydrogen bonds

break and reform at great frequency well

when water is cooled they can't

because they're moving too slow so they

can't break those hydrogen bonds

so now they get stuck and they form a

crystalline

structure and you can see look how much

space is between the water molecules and

that's because of the hydrogen bonds

forcing water molecules to maintain a

certain distance

from other water molecules and this is

important for

marine life specifically because they

can survive under

ice sheets um thinking like the

antarctic or in very very cold re

regions where water freezes marine life

can still

live under those ice sheets

all right so like i said hydrogen bonds

will help form that crystalline

structure so let's do a quick think fair

share or just think on your own

imagine we had a 3d crystalline

structure of ice how many hydrogen bonds

can

one molecule of water make with its

neighboring water molecules

go ahead go ahead try to work through

this one

well hopefully you said four so if you

think about water in a 3d structure it

can form four

bonds with neighboring water molecules

all right and our last property of water

is at its solvent properties

solvent means a dissolving agent in a

solution

and water is a very versatile solvent

sometimes it's called a universal

solvent

and its polar molecules are attracted to

ions and

other polar molecules that it can form

hydrogen bonds with

and here's a quick review of solution

solvent and solute

if you don't remember these terms just

pause it here so you can look at these

all right so remember water can dissolve

other like substances because life

dissolves light so water can interact

with things like

sugars or proteins that contain lots of

oxygen and hydrogen and what water will

do

so here's our water molecules right here

water will form bonds with the sugar

or the protein and it's going to

dissolve it so you can see it forming

all those little hydrogen bonds it's

gonna start pulling it apart

and eventually it will dissolve

all right what about like ionic

compounds well what will happen

is a partially negative oxygen of water

will interact with the positive

atom so in this case uh this will be

with sodium so oxygen will interact with

sodium so notice how all the

red which in this case that's oxygen

look how they're all oriented towards

sodium and then the partially positive

hydrogen will interact with the

the negative atom which in this case is

chlorine so notice here

look at how all the hydrogen are

interacting

with the chlorine or they orient

themselves

so that they're close to chlorine and

then by doing so we go from

this crystal structure of sodium

chloride

to now it being broken apart because of

water

pulling those ions apart

and eventually it will dissolve the ion

okay we're going to work on the water

properties

station lab in class that'll go through

and highlight some of the important

properties that we just covered

okay but before we do that let's go

ahead and look at a

concept check so i want you to pause the

video here

and i want you to try and work through

each of these

all right that's going to be it for this

video

um next video we'll come back and we're

going to start looking at the

elements of life