10th Class Physics: Matter and Energy

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Questions and Answers

Which of the following correctly defines matter?

Anything that occupies space and has mass. (correct)

Anything that can be seen or touched.

Anything that produces energy.

Anything that can change shape.

What are the two types of nature in which matter can exist?

Elemental and compounding.

Solid and liquid.

Gaseous and liquid.

Chemical and physical. (correct)

Which process is an example of change in state of matter?

Melting ice to form water. (correct)

Heating water to boiling point.

Mixing sand and salt.

Dissolving sugar in water.

What is the smallest particle in an element that retains the properties of that element?

Atom. Signup and view all the answers

Which of the following best describes a molecule?

A combination of two or more atoms. Signup and view all the answers

What is true about the state changes of matter?

Energy is released during a change of state. Signup and view all the answers

Which state of matter is characterized by having a definite shape and volume?

Solid. Signup and view all the answers

What is the charge of protons?

Positive Signup and view all the answers

Which particle has no electrical charge?

Neutron Signup and view all the answers

What can be said about the creation and destruction of matter?

Matter can neither be created nor destroyed. Signup and view all the answers

What determines the size or volume occupied by an atom?

Electrons orbiting the nucleus Signup and view all the answers

How many known elements are currently identified?

109 Signup and view all the answers

What defines a molecule?

A combination of two or more atoms Signup and view all the answers

Which of the following correctly describes neutrons?

They add to the weight of the nucleus. Signup and view all the answers

What is the relationship between protons and electrons in a balanced atom?

The number of protons equals the number of electrons. Signup and view all the answers

In what way are protons and neutrons similar?

Both have approximately the same mass. Signup and view all the answers

What is the movement of electrons in a DC current?

Electrons move in one direction only. Signup and view all the answers

What is the primary characteristic of alternating current (AC)?

Electrons move back and forth. Signup and view all the answers

Which materials are classified as conductors?

Copper and aluminum Signup and view all the answers

What is the frequency of AC current commonly found in aircraft?

400Hz Signup and view all the answers

What defines the mass number of an atom?

The total number of protons and neutrons in the nucleus Signup and view all the answers

Which of the following statements about isotopes is true?

Isotopes have the same atomic number but different mass numbers Signup and view all the answers

How are non-conductors characterized?

Electrons are tightly held in outer shells. Signup and view all the answers

Which of the following elements belongs to the family of semiconductors?

Silicon Signup and view all the answers

What happens to an atom when it loses electrons?

It becomes positively charged. Signup and view all the answers

Which term describes the ability of an atom to attract electrons?

Electronegativity Signup and view all the answers

What allows semiconductors to behave sometimes like conductors and sometimes like insulators?

Their structure and arrangement of valence electrons. Signup and view all the answers

What characterizes metals in terms of their electrons?

Some outer electrons are loosely bound and can move easily. Signup and view all the answers

What is essential for the orderly movement of electrons that defines current?

A strong electrical force. Signup and view all the answers

What is an ion?

An atom that has lost or gained an electron. Signup and view all the answers

When an atom is electrically neutral, which of the following is true?

The number of protons equals the number of electrons. Signup and view all the answers

What changes occur to an atom when it becomes an isotope?

It gains or loses neutrons. Signup and view all the answers

What is intrinsic conduction related to?

Movement of electrons due to temperature increase Signup and view all the answers

Which type of compound is formed when a metal reacts with a non-metal?

Ionic compound Signup and view all the answers

What causes elements with deficiencies in their outer shells to be chemically active?

Their tendency to lose or gain electrons Signup and view all the answers

What defines a compound?

A chemical combination of two or more elements Signup and view all the answers

Which of the following is a characteristic of covalent compounds?

They are formed by sharing electrons Signup and view all the answers

What results from the movement of electrons from one atom's outer shell to another in ionic compounds?

Creation of ions Signup and view all the answers

Which of the following substances is classified as a covalent compound?

Water Signup and view all the answers

What is a common property of ionic compounds?

They can conduct electricity when dissolved in water Signup and view all the answers

What describes the molecular arrangement in a liquid state?

Molecules are loosely packed and can move past each other. Signup and view all the answers

What phenomenon allows liquid molecules to remain partially bonded together?

Surface tension Signup and view all the answers

Which statement is true about gases compared to solids and liquids?

Gases expand to fill their container completely. Signup and view all the answers

How does heat energy affect molecular movement in a gas?

It increases the movement and energy of the molecules. Signup and view all the answers

What happens to gas molecules when the pressure is decreased?

They escape more easily and expand. Signup and view all the answers

Which characteristic of gases can be affected by changes in pressure?

Boiling point Signup and view all the answers

What describes the transformation from solid to gas?

Sublimation involves heat and energy addition. Signup and view all the answers

Which statement is correct regarding the properties of solids?

Solids have a definite volume and shape. Signup and view all the answers

Study Notes

Matter and Energy

Matter is anything that occupies space and has mass. Examples include wood, water, and air.
Matter cannot be created or destroyed, but it can change state. Examples are ice changing to water to steam.
Energy is released when matter changes state.
Matter is divided into two categories: chemical nature and physical nature of matter.

Nature of Matter

Matter consists of atoms and molecules.
An atom is the smallest particle of an element that retains the properties of that element.
A molecule is a combination of two or more atoms.

Atoms

Atoms are composed of:
- Nucleus: the center of the atom
- Protons: positively charged particles
- Neutrons: neutral/no charge particles
- Electrons: negatively charged particles
In a balanced atom, the number of electrons orbiting the nucleus is equal to the number of protons inside the nucleus.
Nucleus - each carrying a positive charge are called protons. In addition to the protons, the nucleus usually contains electrically neutral particles called neutrons. Neutrons have the same mass as protons whereas electrons are much smaller.
Neutron - simply adds to the weight of the nucleus.
Proton - has mass same as the neutrons.
Electron - orbits define the size or volume occupied by the atom.

Elements

An element is a substance composed of only one type of atom.
Elements cannot be broken down into simpler substances by chemical means.
Currently, there are 109 known elements.
Atomic Number – the number of protons in an atom'.
Mass Number – the total number of protons and neutrons in an atom's nucleus.
Atomic weight – the total mass of all the sub-atomic particles.
Isotopes- atoms that have the same number of protons but have different numbers of neutrons.

Molecules

Molecules are the smallest units of a substance that still retain the properties of that substance.
Molecules are chemical combinations of two or more atoms.
Molecules are tightly packed together, forming solids, liquids, or gases.
Forces of attraction and repulsion (electromagnetic forces) exist between molecules, and these forces vary depending on the state of the substance.
Example: A molecule of H₂O is formed when two atoms of hydrogen join one atom of oxygen.
Monatomic molecule consists of single type of atom.
Chemical compounds are made up of two or more atoms.

Structure of Atoms

Electrons are arranged in energy levels (shells) around the nucleus, increasing with distance from the nucleus.
Valence electrons are electrons in the outermost shell. They determine the atom's chemical behavior.
The more valence electrons, the more tendency for the atom to seek more electrons.
Valency:
- The bonding capacity of an atom. Usually equal to the number of unpaired electrons in the outermost shell.
- The number of bonds it can make with a monovalent atom.

Atomic Structure

An atom consists mostly of empty space.
At the center is the nucleus.
Protons and neutrons are closely packed within the nucleus.
Electrons orbit the nucleus in all directions.
The number of electrons is equal to the number of protons.
Elements with different numbers of protons and neutrons are called Isotopes.

Atomic Structure - continued

Atoms are electrically neutral because the number of electrons equals the number of protons.
An ion is an atom that has gained or lost one or more electrons giving it a charge.
Electronegativity – tendency of atom to attract electrons to itself.
Electropositivity – tendency to lose its electrons.

States of Matter

Solid:
- Has a fixed volume and shape.
- Molecules are closely packed together
- Low energy state
- Incompressible
Liquid:
- Takes the shape of its container.
- Molecules are loosely packed.
- Higher energy state than solids.
Gas:
- Fills the container completely.
- Molecules are widely dispersed.
- Very high energy state.

Changes Between States

Melting(Solid to Liquid):
- When a solid is heated enough to overcome the forces holding it together, it melts into a liquid. Melting point is the temperature at which this occurs.
Vaporization(Liquid to Gas):
- When atoms move fast enough to break free from intermolecular bonds, becoming a gas. Boiling point is the temperature at which a liquid boils. It depends on pressure above the liquid.
Condensation(Gas To Liquid):
- A gas's temperature decreases to the point where the gas turns into a liquid as molecules slow down. The heat energy released is known as the latent heat of condensation.
Solidification(Liquid to Solid):
- When a liquid's temperature drops enough for its molecules to become a solid. Has a heat of solidification that is equal to the heat of fusion.
Sublimation(Solid to Gas):
- A solid can transform directly into a gas without becoming a liquid. Example: dry ice (solid carbon dioxide).
Deposition (Gas to Solid):
- A gas can transform directly into a solid, without becoming a liquid. Example: water vapor forming ice on a cold window.

Chemical Reactions

Chemical reactions involve the loss or gain of electrons in the outer shells of atoms.
Elements with deficiencies of electrons in their outer shells are very reactive.
Chemical reactions lead to the formation of compounds.
A compound is a chemical combination of two or more different elements.
Examples of compounds: water, methane, sugar, plastics, and rubber.
Types of compounds: metals+ metals(alloy), metals + non-metals (ionic compounds like sodium chloride, acids, salts and alkalis), non-metals + non-metals (covalent compounds like water, methane, sugar, plastics, and rubber).

Semiconductors

Semiconductors are a family of elements that sometimes act like conductors and sometimes like insulators.
Typical semiconductors include silicon and germanium. They have 4 valence electrons in their outer shells.
These electrons are shared between neighbouring atoms, forming a crystal lattice of strongly bonded atoms.
Heat or other energy sources can excite electrons to higher energy states, which leads to increased electron movement, creating "intrinsic" conduction.

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Description

Explore the fundamental concepts of matter and energy in this quiz designed for 10th-grade physics students. Understand how matter interacts, changes state, and the structure of atoms, including protons, neutrons, and electrons. Test your knowledge and deepen your understanding of these essential scientific principles.