Formula and Equations

Question 1

Compound

Answer 1

Substance formed when two or more different elements are chemically combined

Question 2

How can you tell a compound contains two elements?

Answer 2

It ends with -ide

Question 3

How can you tell a compound contains oxygen?

Answer 3

It ends with -ate

Question 4

What can be found using the valency?

Answer 4

The ratio for any two atoms reacting and forming a compound

Question 5

What is the valency of group I?

Answer 5

1

Question 6

What is the valency of group II?

Answer 6

2

Question 7

What is the valency of group III?

Answer 7

3

Question 8

What is the valency of group IV?

Answer 8

4

Question 9

What is the valency of group V?

Answer 9

3

Question 10

What is the valency of group VI?

Answer 10

2

Question 11

What is the valency of group VII?

Answer 11

1

Question 12

What is the valency of group 0/8?

Answer 12

0

Question 13

How do you find the valency of transition metals?

Answer 13

Look at data leaflet - back of periodic table

Question 14

What is valency?

Answer 14

• valency is the combining power of an element
• elements in the same group of the periodic table have the same valency
• the valency of an element is related to how many electrons are in the outer shell

Question 15

What is a simple compound?

Answer 15

Compound containing only two elements

Question 16

How do you write the formulae of compounds?

Answer 16

• write the symbols
• write the valencies in pencil beside the symbols
• swap the valencies
• find the simplest ratio

Question 17

What are molecular ions?

Answer 17

• charged particles containing more than one atom
• compounds containing groups of atoms

Question 18

What are compounds containing three or more elements

Answer 18

• groups of atoms - back of periodic table
• e.g copper sulfate - made up of copper, sulfur and oxygen - sulfate group

Question 19

Where are lists of common groups of atoms found?

Answer 19

On the data leaflet

Question 20

How is the valency found in groups of atoms?

Answer 20

The valency is equal to the charge on the ion
e.g sulfate group - formula SO4 and valency of 2 - written as SO4 2- on data leaflet

Question 21

Why are brackets used in compounds?

Answer 21

If the compound contains two or more of a particular group then brackets must be used

Question 22

pieces of information in a balanced symbol equation

Answer 22

• formulae of reactants and products
• amount or number of particles of each chemical reacting or products forming

Question 23

reactant

Answer 23

Chemical at start

Question 24

products

Answer 24

Particles at end of experiment

Question 25

How is an equation balanced?

Answer 25

step one: from known word equation write down formula of reactants and products step two: count atoms on both sides of equation step three: if number of each type of atom on either side is not the same - balancing the equation is necessary step four: put big numbers before of formula which contains atoms that do not balance - never change small numbers in formula step five: keep balancing until atoms on each side of equation are the same

Question 26

Why do we balance equations in pencil?

Answer 26

You often have to change numbers put in first

Question 27

Diatomic molecules

Answer 27

- **diatomic** - two atoms covalently bonded in molecule - **molecule** - particle that consists of two or more covalently bonded atoms

Question 28

Molecule

Answer 28

particle that consists of two or more covalently bonded atoms

Question 29

HCl

Answer 29

Hydrochloric acid

Question 30

Nitric acid

Answer 30

HNO3

Question 31

Sulfuric acid

Answer 31

H2 SO4

Question 32

relative atomic mass (Ar / RAM)

Answer 32

- term used for elements - Ar = mass number (use periodic table)

Question 33

relative formula mass (Mr / RFM)

Answer 33

- sometimes referred to as relative molecular mass (RMM) - used for compounds - sum of the relative atomic mass of each atom in one molecule of a compound

Question 34

Aqueous

Answer 34

Dissolved in water

Question 35

What is the valency of an element related to?

Answer 35

the valency of an element is **related to how many electrons are in the outer shell**