History of Atom Model Development

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Questions and Answers

Which model is known for its simplicity and visualization of energy levels?

Spherical orbits model

Bohr model (correct)

Modern atomic model

Quantum-mechanical model

Which branch of physics deals with matter and energy at atomic and subatomic levels?

Thermodynamics

Classical Mechanics

Quantum Mechanics (correct)

Astrophysics

What are the three subatomic particles within an atom?

Positrons, Electromagnetic Waves, Neutrons

Protons, Electrons, Neutrons (correct)

Protons, Neutrinos, Electrons

Ions, Electrons, Neutrons

What charge does a Cation have?

Positive Signup and view all the answers

Which property uniquely identifies each element and is equal to the number of protons in its nucleus?

Atomic Number Signup and view all the answers

What is the formula to calculate the number of neutrons in an atom?

$\text{Mass Number} - \text{Atomic Number}$ Signup and view all the answers

What do Anions represent?

A negative charge Signup and view all the answers

Which particle interacts with other atoms to form chemical bonds?

Electrons Signup and view all the answers

What is the symbol for an atom with an excess of 4 electrons?

Si4- Signup and view all the answers

What is the main difference between the Bohr model and the quantum-mechanical model in predicting electron location?

Shape of orbitals Signup and view all the answers

Who first used the word 'atomos' to describe indivisible particles of matter?

Democritus Signup and view all the answers

According to Dalton's atomic theory, atoms of the same element are:

Alike in all aspects Signup and view all the answers

In the Plum Pudding Model, the atom is described as:

A positively charged material with electrons embedded within Signup and view all the answers

The Saturnian Model of the atom was proposed by:

Hantaro Nagaoka Signup and view all the answers

What experiment provided evidence for the existence of a compact nucleus in the atom?

Alpha particle scattering experiment Signup and view all the answers

According to the Nuclear Model of the atom, which of the following statements is true?

Electrons orbit the nucleus in distinct, spherical orbits Signup and view all the answers

Which experiment demonstrated the energy levels of electrons in atoms?

Flame test experiment Signup and view all the answers

Which model of the atom described electrons orbiting the nucleus like the rings of Saturn?

Saturnian Model Signup and view all the answers

Who discovered the electron, which inspired the development of the Plum Pudding Model?

J.J. Thomson Signup and view all the answers

Which scientist's work established that electrons move in distinct, spherical orbits with specific energy levels?

Niels Bohr Signup and view all the answers

What is the average mass of carbon if it were 100% carbon-13?

13 u Signup and view all the answers

If carbon were a 50/50 mix of carbon-12 and carbon-13, what would be its average mass?

12.5 u Signup and view all the answers

What is the actual percentage of carbon-12 in naturally occurring carbon?

98.93% Signup and view all the answers

What is the weighted average atomic mass of lithium, given its abundances are 92.4% lithium-7 and 7.6% lithium-6?

6.924 u Signup and view all the answers

Which isotope of bromine is more common?

Bromine-79 Signup and view all the answers

What is the weighted average atomic mass of chlorine, given its abundances are 75.8% chlorine-35 and 24.2% chlorine-37?

35.484 u Signup and view all the answers

If carbon had a 75% abundance of carbon-12 and a 25% abundance of carbon-13, what would be its average mass?

12.25 u Signup and view all the answers

What is the atomic mass of carbon listed on the periodic table?

12.01 u Signup and view all the answers

If bromine had an atomic mass of 80 u, which isotope of bromine would be more abundant?

Bromine-81 Signup and view all the answers

What is the mass of the chlorine-35 isotope?

35 u Signup and view all the answers

Study Notes

Atomic Structure

The atom is composed of three subatomic particles: electrons, protons, and neutrons.
Electrons are found outside the nucleus, while protons and neutrons are found in the nucleus.
Electrons interact with other atoms, and their properties are:
- Symbol: e-
- Charge: -1e
- Mass: 9.194 x 10^(-31) kg, or approximately 1/1836 u
Protons have a:
- Symbol: p+
- Charge: +1e
- Mass: 1.6726 x 10^(-27) kg, or approximately 1 u
Neutrons have:
- Symbol: n
- Charge: 0
- Mass: 1.6749 x 10^(-27) kg, or approximately 1 u

Properties of Atoms

Atomic Number: the number of protons in an atom, which is unique to each element and determines the element's identity.
Mass Number: the sum of protons and neutrons in an atom, which is unique to each isotope.
Isotopes: atoms of the same element with the same atomic number but different mass numbers.
Ion Notation: 𝐴 𝑋 𝑍, where A is the mass number, X is the chemical symbol, and Z is the atomic number.

Ions

Ions are atoms with an excess or lack of electrons.
Anions have an excess of electrons and a negative charge.
Cations have a lack of electrons and a positive charge.
Ion symbols: Cu²⁺, Mg³⁻, K⁺, etc.

Atomic Mass

Atomic mass is the weighted average of the masses of all the stable isotopes of an element in nature.
It is usually a decimal value.
Units are atomic mass units (u), defined as 1/12th of a carbon-12 atom.

Model Development of the Atom

Democritus proposed the concept of indivisible particles (atoms) in 400 BCE.
John Dalton developed a comprehensive theory of atoms in the early 1800s.
J.J. Thomson discovered the electron in 1897 and proposed the Plum Pudding Model.
Hantaro Nagaoka proposed the Saturnian Model in 1904.
Ernest Rutherford confirmed the existence of a nucleus with alpha particles.
Niels Bohr established that electrons move in distinct, spherical orbits with specific energy levels.

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Description

Explore the historical development of the atom model from Democritus and John Dalton to J.J. Thomson. Learn about key contributions and theories that laid the foundation for modern atomic theory.