STRUKTUR ATOM PART 1 PARTIKEL SUB ATOM DAN NOTASI ATOM

Summary

This educational lecture delves into the structure of atoms, introducing key concepts such as subatomic particles (electrons, protons, neutrons) and atomic notation. It traces the historical development of atomic theory from Democritus to modern scientists like John Dalton, JJ Thomson, Ernest Rutherford, and Henry Moseley. The script explores how atomic mass, isotopes, ions, and molecular masses are determined, along with practical examples of atomic notation and ion formation. The lecture provides a comprehensive understanding of atomic structure and its scientific significance.

Takeaways

• 😀 The concept of atom dates back to the ideas of Democritus, who proposed that all matter is made of indivisible particles called atoms.
• 😀 John Dalton expanded on Democritus' ideas by conducting experiments to establish the scientific theory of atoms, stating that all matter is made up of tiny, indivisible particles.
• 😀 Atoms are composed of subatomic particles: electrons (negative charge), protons (positive charge), and neutrons (no charge). These particles play a key role in determining the atom's structure and properties.
• 😀 JJ Thomson discovered the electron through his cathode ray experiments in 1897, and its charge was measured by Robert Millikan in the oil drop experiment.
• 😀 Ernest Rutherford’s gold foil experiment in 1911 revealed that atoms have a dense, positively charged nucleus, challenging the earlier 'plum pudding' model of the atom.
• 😀 The proton was discovered by Eugen Goldstein in 1886 using cathode ray experiments, and it was established that protons are positively charged and reside in the nucleus.
• 😀 The neutron, a particle with no charge, was discovered by James Chadwick in 1932 through experiments involving alpha particles and atom nuclei.
• 😀 Atomic notation, introduced by Henry Moseley, involves the use of atomic number (Z) and mass number (A) to represent atoms, where A is the sum of protons and neutrons in the nucleus.
• 😀 Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, leading to variations in their mass numbers.
• 😀 The concept of ions was explained, with cations being positively charged ions (formed by losing electrons) and anions being negatively charged ions (formed by gaining electrons).

Q & A

What are the three subatomic particles mentioned in the script?

The three subatomic particles mentioned are electrons, protons, and neutrons.

Who first proposed the concept of the atom?

The concept of the atom was first proposed by Democritus, a philosopher and scientist from the 4th century BCE.

What discovery did John Dalton make regarding atoms?

John Dalton, in 1803, used experimental methods to provide scientific support for the idea that all matter is made up of small particles called atoms.

What are the key properties of an electron?

Electrons are negatively charged, with a charge of -1.6 x 10^-19 Coulombs, and a mass of approximately 9.9 x 10^-28 grams.

How were the properties of electrons determined?

The properties of electrons were determined through experiments like the cathode ray tube experiments conducted by J.J. Thomson and the oil drop experiment by Robert Millikan.

Who discovered the proton and what was its key property?

The proton was discovered by Eugen Goldstein in 1886. Protons have a positive charge and a mass of approximately 1.67 x 10^-24 grams.

What role did Ernest Rutherford play in the understanding of atomic structure?

Ernest Rutherford conducted the gold foil experiment in 1909, which led to the discovery that atoms have a small, dense nucleus, with most of the atom consisting of empty space.

What did Rutherford conclude about the atom’s structure from his experiment?

Rutherford concluded that the atom has a small, dense nucleus (containing protons and neutrons) at its center, and most of the atom is empty space.

How is the notation of an atom written, and what do the symbols represent?

The notation of an atom is written as A/Z X, where A is the mass number (protons + neutrons), Z is the atomic number (number of protons), and X is the chemical symbol of the element.

What is the difference between isotopes, isobars, and isotoners?

Isotopes are atoms of the same element with different mass numbers. Isobars are atoms of different elements with the same mass number. Isotones are atoms with the same number of neutrons.