Physics Definition and Atom History CH1

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Questions and Answers

What determines the chemical element of an atom?

The number of protons (correct)

The number of neutrons

The arrangement of shells

The number of electrons

Which shell has the highest carrying capacity for electrons according to the arrangement provided?

N shell (correct)

L shell

K shell

O shell

What is true about isotopes?

They have the same number of protons but different number of electrons.

They have the same number of protons but different number of neutrons. (correct)

They are always electrically charged.

They have different numbers of protons.

What is the maximum number of electrons that can occupy the L shell?

8 Signup and view all the answers

What happens to the total number of electrons in an atom when it is in its normal state?

It is exactly equal to the number of protons. Signup and view all the answers

What are the two main parts of an atom?

Nucleus and orbiting electrons Signup and view all the answers

What charge do protons have?

Positive charge Signup and view all the answers

Which force pulls electrons toward the nucleus?

Electrostatic force Signup and view all the answers

Which statement is true regarding atomic mass?

It is primarily concentrated in the nucleus. Signup and view all the answers

What is the overall charge of an atom in its natural state?

Electrically neutral, equal protons and electrons Signup and view all the answers

What role do centrifugal forces play in an atom?

They pull electrons away from the nucleus. Signup and view all the answers

Which orbiting electrons experience a greater electrostatic force?

Electrons in the K-shell Signup and view all the answers

Neutrons are characterized by which property?

No electrical charge Signup and view all the answers

What is the primary focus of physics?

The properties and forms of motion of matter Signup and view all the answers

Which four substances did early Greek scientists believe composed all matter?

Earth, water, air, and fire Signup and view all the answers

What does the term 'atom' mean in Greek?

Indivisible Signup and view all the answers

According to John Dalton, how did elements behave?

All atoms of an element were identical and reacted the same way Signup and view all the answers

What was J.J. Thomson's contribution to atomic theory?

Proposed that electrons are part of all atoms Signup and view all the answers

How did Rutherford describe the structure of the atom?

As mostly empty space with a central nucleus Signup and view all the answers

In Bohr's atomic model, how do electrons behave?

They revolve around the nucleus in fixed paths or energy levels Signup and view all the answers

What was the common belief about atomic structure during the late 1800s?

Atoms were solid and indivisible Signup and view all the answers

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

N = A - Z Signup and view all the answers

How many maximum electrons can the third shell (M-shell) hold?

18 Signup and view all the answers

Which statement about electron binding energy is correct?

Removing an outer-shell electron requires less energy than removing an inner-shell electron. Signup and view all the answers

What determines the frequency of electromagnetic radiation?

The number of wave oscillations per unit time. Signup and view all the answers

Which of the following best describes electromagnetic radiation?

A transverse wave with electric and magnetic fields oscillating perpendicular to its direction of motion. Signup and view all the answers

What is the relationship between wavelength, frequency, and the speed of light?

c = f * λ Signup and view all the answers

What happens when an electron moves from an outer shell to an inner shell?

It loses energy and can emit electromagnetic radiation. Signup and view all the answers

Which of the following statements is true regarding the nucleus of an atom?

It contains most of the atom's mass, primarily from neutrons and protons. Signup and view all the answers

Study Notes

Definition of Physics

Physics deals with the fundamental properties and motion of matter.
Matter is all physical substances around us that have mass and occupy space.
The universe is composed of matter and energy.

History of the Atom (Greek Atom)

Ancient Greek scientists believed matter was composed of four elements: earth, water, air, and fire.
These elements combined in various proportions and were modified by wet, dry, hot, and cold essences.
The concept of "atom" meaning indivisible, was used to describe the smallest part of these elements.
Each type of atom was represented by a specific symbol.

Dalton's Atom

In 1808, John Dalton proposed a model based on experiments.
Elements are classified according to integral values of atomic mass.
An element consists of identical atoms that react chemically in the same way.
For example, all oxygen atoms are alike.

Thomson's Atom

In the late 1890s, J.J. Thomson discovered electrons as an integral part of atoms.
He visualized the atom as a "plum pudding" model, where electrons (plums) are embedded within a positively charged mass (pudding).
The number of electrons balances the positive charge, making the atom electrically neutral.

Rutherford's Atom

Rutherford's model suggested an atom is mostly empty space with electrons orbiting a small, dense, positively charged nucleus.

Bohr's Atom

In 1913, Niels Bohr refined Rutherford's model.
Bohr's model likened the atom to a miniature solar system, with electrons revolving in prescribed orbits or energy levels.
For simplicity, Bohr's model, while not perfectly accurate, represents the structure effectively.
This model was later refined by quantum chromodynamics (QCD)

The Atom (Structure)

Atoms have two main components: a nucleus and orbiting electrons.
The nucleus contains protons and neutrons (called nucleons).
Neutrons have no electrical charge, while protons carry a positive charge.
Electrons have a negative charge.
Electrons are arranged in energy levels or shells.

Atomic Particles

Protons: Larger and heavier than electrons, have a positive charge (+), and are located in the nucleus.
Neutrons: Large and heavy, similar to protons but have no electrical charge, found in the nucleus.
Electrons: Tiny and light, carry a negative charge (-), orbit the nucleus in shells.

Electron Binding Energy

Energy required to remove an electron from an atom.
Inner-shell electrons have higher binding energy than outer-shell electrons.
Energetic particles can knock out inner-shell electrons only if their energy equals or exceeds the electron binding energy.

Shells

Each atomic shell has a principal quantum number, starting with 1 for the K-shell, 2 for the L-shell and so forth.
Electrons in a given shell can have a certain maximum capacity, based on the 2n^2 rule.
The electron distribution is: 2, 8, 18, 32, 21, 9, and 2 in successive shells.

Electromagnetic Radiation

Electrons transitioning between energy shells emit electromagnetic radiation.
This radiation is quantized (exists in discrete energy packets called photons).
Electromagnetic radiation is a transverse wave, where the electric and magnetic fields vibrate perpendicular to the direction of the wave motion.

Atomic Properties

Atoms are electrically neutral in normal state (number of electrons = number of protons).
The atomic number corresponds to the number of protons.
Isotopes have the same number of protons but different numbers of neutrons.
The mass number is the sum of protons plus neutrons.

Summary of Atomic Structure

Atoms have a dense, positively charged nucleus where most of the mass is concentrated.
The atom is essentially empty space, occupied mostly by electrons orbiting the nucleus.
Shells determine probable electron locations based on quantized energy levels.

Additional notes

Diagrams and figures are important visual aids for understanding the concepts.
Practice calculations related to atomic numbers, mass numbers, isotopes etc.

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Description

Explore the foundational concepts of physics, including the properties and motion of matter. Delve into the historical development of atomic theory from Ancient Greece to Dalton and Thomson's models. This quiz covers significant milestones in our understanding of the atomic structure.