science y9 t1

Question 1

How do ionic compounds form?

Answer 1

A cation (positive ion) and an anion (negative ion) are attracted to each other due to electrostatic forces, forming an ionic bond.

Question 2

What is the chemical formula of lithium oxide?

Answer 2

Li₂O (Lithium Oxide).

Question 3

How does the “swap and drop” method work for writing ionic compounds?

Answer 3

Write the charges of the ions, swap them, and drop them as subscripts to balance the charges.

Question 4

What are polyatomic ions?

Answer 4

Ions made of more than one atom that stay together in compounds.

Examples:

NO₃⁻ (Nitrate)

Question 5

How do you write formulas with polyatomic ions?

Answer 5

Use brackets when there’s more than one polyatomic ion in the formula.
Example:

Mg(OH)₂ (Magnesium Hydroxide)

Question 6

What is the difference between ionic and covalent compounds?

Answer 6

Ionic compounds: Electrons move from a metal to a non-metal.
Covalent compounds: Electrons are shared between non-metals to get full outer shells.

Question 7

How do we name covalent compounds?

Answer 7

Use prefixes to show the number of atoms:

First atom: Add a prefix only if there’s more than one.
Second atom: Always use a prefix and add “-ide” at the end.
Example:

CO₂ → Carbon dioxide

Question 8

What are the prefixes for naming covalent compounds?

Answer 8

Mono- = 1
Di- = 2
Tri- = 3
Tetra- = 4
Penta- = 5
Hexa- = 6

Question 9

What is metallic bonding?

Answer 9

Occurs in metals.
Metal atoms form a lattice and lose their outermost electrons.
This forms a “sea of electrons” that holds everything together.

Question 10

What are the three types of bonding?

Answer 10

Ionic, Covalent Molecular, Metallic

Question 11

Why do lattice structures have high melting and boiling points?

Answer 11

Because strong bonding in the lattice requires a lot of energy to break.

Question 12

What are covalent networks?

Answer 12

Special covalent structures that form lattices instead of molecules.
They have extremely high melting and boiling points.
Examples: Diamond, Graphite.

Question 13

What do subscript numbers in a chemical formula apply to?

Answer 13

The element directly on the left.
Example: Cl₂ means two chlorine atoms.

Question 14

What does a coefficient in front of a compound affect?

Answer 14

It multiplies the whole compound.
Example: 2HCl → two H, two Cl.

Question 15

How does a subscript outside brackets affect a compound?

Answer 15

It multiplies everything inside the brackets.
Example: Mg(OH)₂ → one Mg, two O, two H.

Question 16

What does the Law of Conservation of Mass state?

Answer 16

The number and type of atoms at the start of a reaction must be the same after the reaction.

Question 17

Why do we balance chemical equations?

Answer 17

To make sure both sides have equal numbers of atoms.

Question 18

What can we change when balancing equations?

Answer 18

We cannot change the formula of compounds, only the coefficients in front.

Question 19

Miss Conran’s balancing tip

Answer 19

Leave hydrogen (H) and oxygen (O) until last!

Question 20

What are atoms made up of?

Answer 20

Positively charged nucleus
Electron shells that surround the nucleus

Question 21

What are the three subatomic particles?

Answer 21

Protons (P)
Electrons (E)
Neutrons (N)

Question 22

What are the properties of protons?

Answer 22

Relative charge: +1
Relative mass: 1
Determines the element of the atom

Question 23

What are the properties of neutrons?

Answer 23

Relative charge: 0 (neutral)
Relative mass: 1
Helps stabilize the nucleus
The number of neutrons can vary between atoms of the same element

Question 24

What are the properties of electrons?

Answer 24

Relative charge: -1
Relative mass: ~0
Balances the positive charge of the nucleus

Question 25

What is the atomic number?

Answer 25

The atomic number is the number of protons (which is also equal to the number of electrons in a neutral atom).

Question 26

What is the mass number?

Answer 26

Mass number = Number of protons + Number of neutrons

Question 27

What is the nuclear symbol notation?

Answer 27

X = Element symbol M = Mass number A = Atomic number

Question 28

How do electrons arrange themselves in an atom?

Answer 28

Electrons arrange themselves in shells, filling up from the innermost shell first.

Question 29

What is the maximum number of electrons each shell can hold?

Answer 29

1st shell: 2 electrons 2nd shell: 8 electrons 3rd shell: 8 electrons 4th shell: 2 electrons

Question 30

What are valence electrons?

Answer 30

Valence electrons are the electrons in the outermost shell of an atom.

Question 31

Why do atoms gain or lose electrons?

Answer 31

Atoms gain or lose electrons to become more stable and achieve a full outer shell of electrons.

Question 32

What are ions?

Answer 32

Atoms that have gained or lost electrons. Cations: Positively charged ions. Anions: Negatively charged ions.

Question 33

What is the rule for naming anions?

Answer 33

The ending changes to "-ide". Examples: Oxygen → Oxide

Question 34

How can we determine the charge of an ion from the periodic table?

Answer 34

1 +1 2 +2 13 +3 14 Covalent 15 -3 16 -2 17 -1 18 No ions formed

Question 35

Why do transition metals (Groups 3-12) need Roman numerals?

Answer 35

They can form multiple ions, so we use Roman numerals to indicate the charge.

Question 36

What are metalloids?

Answer 36

Elements that have properties of both metals and non-metals.

Question 37

What are the four different states of matter used in balanced equations?

Answer 37

Solid (s), Liquid (l), Gas (g), Aqueous (aq).

Question 38

What does (s) stand for in chemical equations?

Answer 38

Solid.

Question 39

What are the characteristics of a solid in chemical equations?

Answer 39

Metal by itself Precipitate Insoluble ionic salt

Question 40

What is the test for carbon dioxide (CO₂)?

Answer 40

The limewater test: CO₂ is bubbled into clear limewater, which turns cloudy.

Question 41

What is the test for hydrogen (H₂)?

Answer 41

The pop test: H₂ is collected, and when a flame is introduced, it makes a loud pop noise.

Question 42

What is the test for oxygen (O₂)?

Answer 42

The glowing splint test: O₂ is collected, and a lit splint is blown out. When the glowing splint is introduced to O₂, it reignites.

Question 43

What are isotopes?

Answer 43

Atoms of the same element with the same number of protons but different numbers of neutrons.

Question 44

What makes an isotope unstable?

Answer 44

If the number of neutrons is too high or too low, the nucleus becomes unstable.

Question 45

What happens to unstable isotopes?

Answer 45

Unstable isotopes are radioactive and undergo decay.

Question 46

What is radioactive decay?

Answer 46

The process where an unstable nucleus tries to become more stable by releasing ionizing radiation.

Question 47

What types of particles can radioactive decay emit?

Answer 47

Alpha (α) particles Beta (β) particles Gamma (γ) radiation

Question 48

What is alpha (α) decay?

Answer 48

The nucleus emits an alpha particle (²⁴He). Alpha particle = 2 protons + 2 neutrons. The atom loses 2 protons and 2 neutrons, changing to a new element.

Question 49

What are the properties of alpha (α) particles?

Answer 49

Slow-moving (heavy) Very strong ionizing ability (dangerous) Stopped by air, skin, or paper

Question 50

What is beta (β) decay?

Answer 50

A neutron turns into a proton and releases a beta particle (⁰₋₁β) (a high-energy electron). The atom gains a proton and loses a neutron.

Question 51

What are the properties of beta (β) particles?

Answer 51

Medium ionizing power Moderate penetration (stopped by aluminum) Moderate speed

Question 52

What is gamma (γ) radiation?

Answer 52

A high-energy electromagnetic wave emitted when the nucleus has excess energy after alpha or beta decay. Does not change the element, just releases extra energy.

Question 53

What are the properties of gamma (γ) radiation?

Answer 53

Low ionizing ability Very high energy, high penetration (stopped by lead) Moves at the speed of light

Question 54

What is radioactive decay?

Answer 54

A spontaneous process that cannot be controlled and is not affected by external factors like temperature.

Question 55

What is half-life?

Answer 55

The time it takes for half of a radioactive sample to decay.

Question 56

How much of a sample remains after 1, 2, and 3 half-lives?

Answer 56

1 half-life: 50% 2 half-lives: 25% 3 half-lives: 12.5%