c3

Question 1

define element

Answer 1

contains only one kind of atom

Question 2

define compound

Answer 2

contains two or more kinds of atoms, typically chemically bonded

Question 2

explain the structure of metallic elements

Answer 2

-strong metallic bonds hold the metal atoms in a lattice.
-no molecules, hence no intermolecular forces.

Question 3

describe the atoms in group 8 (or group 0)

Answer 3

• exist as individual atoms only.
• dont bond with other atoms as they already have a full outer shell.
• weak intermolecular forces between the atoms.

Question 4

describe the atoms in group 7

Answer 4

-diatomic molecules
-strong covalent bonds joining one Cl to the other, but weak intermolecular forces between the Cl2 molecules.

Question 5

what are the other diatomic molecules that aren’t in group 7?

Answer 5

N2, O2 and H2

Question 6

what happens in ionic bonding?

Answer 6

metal + non metal
give/takes electrons

Question 7

what happens in covalent bonding?

Answer 7

non metal + non metal
shares electrons?

Question 8

what happens in alloy mixture?

Answer 8

metal + metal

Question 9

explain atom

Answer 9

smallest particle of an element
have a nucleus containing protons and neutrons
electrons orbit in shells

Question 10

define molecule

Answer 10

particle consisting of two/more non-metal atoms joined by covalent bonding.

Question 11

what is the chemical formula of hydrochloric acid?

Answer 11

HCO

Question 12

what is the chemical formula of nitric acid?

Answer 12

HNO3

Question 13

what is the chemical formula of methane?

Answer 13

CH4

Question 14

what is the chemical formula of water?

Answer 14

H20

Question 15

what is the chemical formula of ammonia

Answer 15

NH3

Question 16

what is the chemical formula of sulfuric acid?

Answer 16

H2SO4

Question 17

how much charge is there for each group on the periodic table? and how do you work it out?

Answer 17

group 1 - +1
group 2 - +2
group 3 - +3
(group 4 usually doesn’t form ions)
group 5 - 3-
group 6 - 2-
group 7- 1-
the group number is equal to how many electrons there are in the outermost cell, and the charge is dependent on how many they have to lose or gain to have a full outer shell.

Question 18

how do you write ionic formulae?

Answer 18

you need to balance the charges on the ions so that the total is 0
you may need to add a subscript number and use brackets for compound ions

Question 19

what is the law of conservation of mass?

Answer 19

-atoms can’t be created or destroyed by chemical reactions
-the same atoms are present at the start and end of a reaction, they are just rearranged to form different substances
-the total mass stays the same

Question 20

how can you investigate conservation of mass?

Answer 20

in a closed system (where no substances can enter/leave during the reaction)

Question 21

what are the two ways that you can investigate conservation of mass?

Answer 21

-a beaker if the reactants are in solution and no gases are formed
-a flask attached to a gas syringe to stop gases produced from escaping.

Question 22

why can the mass appear to change?

Answer 22

if you don’t have a closed system, then the mass can appear to change

Question 23

why could the mass descrease?

Answer 23

if a gas is produced and escapes the mass can appear to decrease

Question 23

why could the mass descrease?

Answer 23

if a gas is produced and escapes the mass can appear to decrease

Question 24

why could the mass increase?

Answer 24

if a substance reacts with oxygen in the air, the mass of the oxygen atoms causes the mass of the product to increase.

Question 25

what is empirical formula?

Answer 25

the most simplified version of a formula

Question 26

state the steps for writing ionic equations

Answer 26

1) start with word equation
2) write the balanced symbol equation with state symbols
3) break down all (aq) compounds into ions
4) cancel spectator ions
5) write out “leftovers” as net ionic equation

Question 27

how can ionic equations be applied?

Answer 27

-often used to represent neutralization reactions
-also used to represent precipitation reaction

Question 28

what are half equations?

Answer 28

half equations show the change that happens to one element. In a half equation, elements either lose or gain electrons

Question 29

define oxidation

Answer 29

oxidation is loss of electrons

Question 30

define reduction

Answer 30

reduction is gain of electrons

Question 31

define oxidizing agent

Answer 31

the oxidizing agent oxidases something else by getting reduced itself

Question 32

define reducing agent

Answer 32

the reducing agent reduces something else by getting reduced

Question 33

define mole

Answer 33

a mole is defined as the amount of substance that contains the same number of entities as there are atoms in 12g of carbon-12

Question 34

what is Avogadro’s constant?

Answer 34

6.02× 10 (23)
(10 to the power of 23)

Question 35

what is the mass of 1 mole of a substance

Answer 35

the mass of one mole of a substance is its relative atomic/formula mass

Question 36

what is the mass of one mole of carbon atoms?

Answer 36

12g

Question 37

what is the mass of one mole of oxygen molecules

Answer 37

32g

Question 38

what is the relation between mass, mr and mole

Answer 38

mass
mr I mole