Physics Lesson 1 Exercises

Questions and Answers

At what temperature do the numerical readings on a Celsius thermometer and a Fahrenheit thermometer equal each other?

32 degrees

100 degrees

0 degrees

-40 degrees (correct)

What is the mass of oil with a specific gravity of 0.7 if there are 325 ml of oil present?

0.456 kg

0.650 kg

0.231 kg (correct)

0.910 kg

Which of the following is NOT a postulate of Dalton's Atomic Theory?

Compounds are formed from atoms of different elements.

Atoms can change into different elements. (correct)

All atoms of an element have identical properties.

Atoms are extremely small, indivisible particles.

What is the conversion of 3 angstroms to nanometers?

0.3 nm Signup and view all the answers

What is the density of copper if its mass is determined to be $125$ grams and its volume is $14$ cm³?

8.92 g/cm³ Signup and view all the answers

Which scientist is considered the father of modern atomic theory?

John Dalton Signup and view all the answers

How can compounds be formed according to Dalton's Atomic Theory?

By combining atoms in small whole-number ratios Signup and view all the answers

What does the term 'atoms' refer to in the context of atomic theory?

Indivisible particles of matter Signup and view all the answers

What role does the strong nuclear force play in atomic nuclei?

It binds protons and neutrons together. Signup and view all the answers

Which statement best describes the neutron as discovered by James Chadwick?

It is electrically neutral and has a mass comparable to protons. Signup and view all the answers

In the Bohr model of the atom, how are electrons arranged around the nucleus?

In fixed, circular orbits corresponding to energy levels. Signup and view all the answers

What is the significance of the Schrödinger equation in quantum mechanics?

It governs the behavior of wave functions for electrons. Signup and view all the answers

Which of the following best describes the weak nuclear force?

It is responsible for processes like beta decay. Signup and view all the answers

How did James Chadwick confirm the presence of neutrons?

Through bombardment of beryllium with alpha particles. Signup and view all the answers

What did the gold foil experiment demonstrate about atomic structure?

Most of the nucleus is empty space. Signup and view all the answers

What concept is illustrated by the planetary model proposed by Neils Bohr?

Electrons occupy fixed orbits around the nucleus. Signup and view all the answers

According to the law of definite proportions, different samples of the same compound will have what characteristic?

Only constituent elements in the same proportion Signup and view all the answers

What does the law of multiple proportions state about two elements that can form multiple compounds?

The ratios of masses are whole small numbers Signup and view all the answers

Who is credited with the discovery of electrons?

J.J. Thomson Signup and view all the answers

What model of the atom did J.J. Thomson propose?

Plum-pudding model Signup and view all the answers

What was a major conclusion from Ernest Rutherford's Gold Foil Experiment?

Most of the mass of the atom is in the nucleus Signup and view all the answers

What charge does a proton have compared to an electron?

Positive, opposite to that of the electron Signup and view all the answers

In the context of atomic structure, what was determined about protons in relation to the nucleus?

Protons cannot leave the nucleus due to the strong nuclear force Signup and view all the answers

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

The majority of an atom's volume is empty space Signup and view all the answers

What does the atomic number of an element represent?

Number of protons in the nucleus Signup and view all the answers

Which of the following statements about isotopes is correct?

Isotopes have the same number of protons but different numbers of neutrons Signup and view all the answers

What is the charge of a neutron?

No charge Signup and view all the answers

When calculating the average atomic mass, which of the following factors is NOT considered?

Number of electrons Signup and view all the answers

What type of molecule is formed by combining more than two atoms?

Polyatomic molecule Signup and view all the answers

Which term describes an atom or group of atoms that possesses a net positive charge?

Cation Signup and view all the answers

What happens to the number of electrons in a neutral atom compared to the number of protons?

It is always equal Signup and view all the answers

Which of the following correctly defines a molecule?

The smallest particle of an element or compound with stable existence Signup and view all the answers

Study Notes

Atomic Theory

Atoms are the fundamental building blocks of matter, originating from the Greek word "atomos," meaning indivisible.
Democritus proposed that matter is composed of tiny, indivisible particles around 470 - 400 BC.
John Dalton, known as the Father of Modern Atomic Theory, published his atomic theory in 1808, emphasizing the existence of atoms, their identical properties within elements, and the conservation of atoms during reactions.

Dalton's Atomic Theory

Elements comprise very small, indivisible particles called atoms.
Atoms of the same element have identical properties, differing from those of other elements.
Atoms cannot be created or destroyed.
Compounds arise from specific ratios of different atoms.
The composition of compounds is consistent in relative proportions of atoms.

Relevant Laws

Law of Definite Proportions (Joseph Proust): Same compound samples contain components in fixed proportions.
Law of Multiple Proportions: When two elements form multiple compounds, the mass ratios of one combined with a fixed mass of the other are whole numbers.

Fundamental Particles

Atoms consist of electrons, protons, and neutrons.
J.J. Thomson discovered electrons in 1897 through cathode ray experiments and proposed the Plum-Pudding Model of the atom.
Ernest Rutherford's Gold Foil Experiment (1911) revealed that:
- Atoms are mostly empty space.
- Most mass is concentrated in a dense, positively charged nucleus.
- Electrons orbit surrounding the nucleus.

Nuclear Structure

Protons carry a positive charge; their mass is roughly 1840 times that of electrons.
Protons remain within the nucleus due to a strong nuclear force, which also binds neutrons and protons together.
Weak nuclear force governs processes like beta decay.

Atomic Models

Neils Bohr introduced the Planetary Model in 1913, defining fixed electron orbits with quantized energy levels.
Erwin Schrödinger developed the Quantum Model, describing electron behavior via wave functions, quantifying electron energy levels through the Schrödinger equation.

Discovery of Neutrons

James Chadwick discovered neutrons in 1932, showing they are electrically neutral and of similar mass to protons.

Atomic Number and Mass

Atomic Number: Number of protons in an atom's nucleus.
Mass Number: Total count of protons and neutrons; in neutral atoms, protons equal electrons.
Isotopes are variations of elements with the same protons but different neutrons, yielding diverse atomic masses.

Molecules

Molecules are the smallest units of compounds that retain stable properties.
Can be diatomic (two atoms) or polyatomic (more than two atoms).

Ions

Ions are atoms or groups with a net charge.
Types of Ions:
- Cations: Positive net charge.
- Anions: Negative net charge.

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Test your knowledge with these exercises from Physics Lesson 1. You'll tackle questions involving temperature conversions, mass calculations, and the definition of power. Improve your understanding of key physics concepts through practical problems.