physical changes

Question 1

How many electrons can fit on the third shell?

Answer 1

18

The maximum number of electrons in a shell is given by the formula 2n², where n is the shell number.

Question 2

How is the periodic table arranged?

Answer 2

In order of atomic number

The atomic number represents the number of protons in an atom.

Question 3

What are groups on the periodic table called?

Answer 3

The columns

Groups contain elements with similar chemical properties.

Question 4

What are the rows on the periodic table called?

Answer 4

The periods

Each period corresponds to the number of electron shells in the elements.

Question 5

What does the group number tell you about an atom of an element in that group?

Answer 5

The number of electrons on the outer shell

This affects the chemical behavior of the element.

Question 6

What does the period tell you about an atom of an element in that group?

Answer 6

The number of shells the atom has

This indicates the energy levels of the electrons.

Question 7

What is meant by a physical change?

Answer 7

When the particles rearrange but no new chemicals are formed

Physical changes are usually reversible.

Question 8

Give two examples of physical changes.

Answer 8

• Changes of state (e.g., melting or boiling)
• Separating mixtures (e.g., filtration, distillation)

These processes alter the form of a substance but not its chemical composition.

Question 9

What is a chemical reaction?

Answer 9

A reaction where a new substance is made

Chemical reactions involve the rearrangement of atoms.

Question 10

What is a solution?

Answer 10

Formed when a solid dissolves in a liquid

Solutions are homogeneous mixtures.

Question 11

What is a solute?

Answer 11

The solid that dissolves in a liquid

In a solution, the solute is present in a lesser amount.

Question 12

What is a solvent?

Answer 12

The liquid a solid dissolves into

Solvents are typically present in greater amounts in a solution.

Question 13

What word do we use to describe how easily a solute dissolves?

Answer 13

Solubility

Solubility can vary based on temperature and pressure.

Question 14

What affects the solubility of a solid?

Answer 14

Temperature

Generally, higher temperatures increase solubility.

Question 15

How does temperature affect the solubility of a solid?

Answer 15

The higher the temperature, the greater the solubility

This is particularly true for most solid solutes in liquid solvents.

Question 16

What is a saturated solution?

Answer 16

One in which more solute cannot dissolve

A saturated solution has reached its maximum solute capacity at a given temperature.

Question 17

What is evaporation?

Answer 17

When liquid turns to a gas at the surface of a liquid

Evaporation occurs at any temperature.

Question 18

Give 3 ways evaporation is different from boiling.

Answer 18

• Happens at any temperature
• Only happens at the surface of the liquid
• No bubbles of gas are seen

Boiling occurs at a specific temperature and throughout the liquid.

Question 19

What is an atom?

Answer 19

Smallest piece of an element

Atoms are the basic building blocks of matter.

Question 20

What is an Element?

Answer 20

Substance made of 1 type of atom. Listed on the Periodic Table

Elements are pure substances that cannot be broken down into simpler substances.

Question 21

What is a Compound?

Answer 21

Substance made of 2 or more elements chemically joined

Compounds have different properties than the elements that form them.

Question 22

What is meant by pure?

Answer 22

Substance made of 1 type of particle

A pure substance cannot be separated into other materials by physical means.

Question 23

What is meant by a mixture?

Answer 23

Two or more different particles not chemically joined in a space e.g. salt water, air

Mixtures can be separated by physical means.

Question 24

What is meant by a Molecule?

Answer 24

Particle made of more than one atom chemically joined. The elements are usually non-metals

Molecules can consist of the same or different types of atoms.

Question 25

What is meant by a Particle?

Answer 25

General name for any small piece of matter. Can be atoms or molecules (or ions) ## Footnote Particles are the smallest units of substances.

Question 26

What is the Periodic Table?

Answer 26

List of all known elements with their symbols ## Footnote The Periodic Table organizes elements based on their atomic number and properties.

Question 27

What is meant by a Formula?

Answer 27

How chemists show the combination of elements in a particle e.g. CuSO4 or NaCl ## Footnote Formulas represent the ratio of elements in a compound.

Question 28

How do the properties of a compound relate to the elements they are made from?

Answer 28

There is no relationship - compounds can have very different properties from the elements they are made from ## Footnote This is due to the chemical bonds and interactions that occur in compounds.

Question 29

What are the components of an atom?

Answer 29

Electron, Neutron, Proton, Nucleus ## Footnote Electrons are negatively charged, neutrons have no charge, and protons are positively charged.

Question 30

What is the mass of a proton?

Answer 30

1 ## Footnote Protons have a mass of approximately 1 atomic mass unit (amu).

Question 31

What is the mass of a neutron?

Answer 31

1 ## Footnote Neutrons also have a mass of approximately 1 atomic mass unit (amu).

Question 32

What is the mass of an electron?

Answer 32

Nearly zero ## Footnote Electrons have a very small mass compared to protons and neutrons.

Question 33

What is the charge of a proton?

Answer 33

+1 ## Footnote Protons carry a positive electrical charge.

Question 34

What is the charge of a neutron?

Answer 34

0 ## Footnote Neutrons are neutral and do not have an electric charge.

Question 35

What is the charge of an electron?

Answer 35

-1 ## Footnote Electrons carry a negative electrical charge.

Question 36

What is between the shells of electrons?

Answer 36

Nothing ## Footnote The space between electron shells is a vacuum.

Question 37

How do we calculate the mass number of an atom?

Answer 37

Number of protons + number of neutrons ## Footnote The mass number reflects the total number of protons and neutrons in the nucleus.

Question 38

How do we calculate the atomic number of an atom?

Answer 38

Number of protons ## Footnote The atomic number determines the identity of an element.

Question 39

How does the number of protons compare to the number of electrons in an atom?

Answer 39

They are the same ## Footnote This balance ensures that the atom is electrically neutral.

Question 40

How many electrons can fit on the first shell?

Answer 40

2 ## Footnote The first electron shell can hold a maximum of 2 electrons.

Question 41

How many electrons can fit on the second shell?

Answer 41

8 ## Footnote The second electron shell can hold a maximum of 8 electrons.

Question 42

what is a compound?

Answer 42

a substance made of two or more atoms chemically joined

Question 43

what is a pure substance

Answer 43

a substance made of one type of molecule

Question 44

what is a molecule

Answer 44

a molecule is a particle made of more than one type of atom chemically joined together they are usually non metals with weak forces of attraction against them

Question 45

what does the top number represent in the periodic table

Answer 45

the mass number

Question 46

what is in the nucleus?

Answer 46

the protons