Symbols, Formulae And Equations

Question 1

What is an element?

Answer 1

An element is a substance that consists of only one type of atom. Elements cannot be broken down into simpler substances by chemical means.

Question 2

What is a compound

Answer 2

A compound is a substance that consists of two or more different elements chemically combined.

Question 3

What is a diatomic molecule?

What are the diatomic molecules?

Answer 3

Two atoms covalently bonded in a molecule.
Some elements only exist in diatomic bonds, such as:
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Florine (F2)
Chlorine (Cl2)
Bromine (Br2)
Iodine (I2)

Question 4

What does a chemical formulae tell us?

Answer 4

The names of the elements present

The number of each type of atom present

Question 5

What is Valency?

Answer 5

Valency is a measure of the ability of an atom to join with other atoms.

Remember
Group: 1 2 3 4 5 6 7
Valency: 1 2 3 4 3 2 1

Question 6

How do you work out the formulae of compounds?

Answer 6

Copper (II) chloride
/ \
Cu Cl
v=2 v=1
\ /
CuCl2

Question 7

Where do you find the Valencies of complex compounds (molecular ions)

Answer 7

Back of periodic table

Question 8

What do cations combined with single non-metals end with?

Answer 8

-ide

Question 9

What do cations combined with oxygen end with?

Answer 9

-ate or -ide

Question 10

What do cations combined with Hydroxide end with?

Answer 10

Hydroxide, duh. It’s in the name.

Question 11

Write a word equation for this reaction-
Sulfur dioxide can be prepared by reacting hydrochloric acid with sodium sulfite. The other products are sodium chloride and water.

Answer 11

Hydrogen chloride + sodium sulfite —> sulfur dioxide + sodium chloride + water

Question 12

Metal + acid —>
Acid + base —>
Acid + metal carbonate —>

Answer 12

Salt + hydrogen
Salt + water
Salt + water + carbon dioxide

Question 13

List the 3 steps for balancing equations.

Answer 13

Step 1. Write down the word equation

Step 2. Write down the relevant symbols and formulae underneath

Step 3. Balance the equation by making sure that the total number of each type of element is the same on both sides of the arrow.

Question 14

What are the 5 steps for writing ionic equations

Answer 14

Step 1: write down the word equation for the reaction

Step 2: write down the balanced symbol equation for the reaction, including state symbols (aq) (l) (s)

Step 3: split the ionic compounds into their individual ions in the equation.

Step 4: highlight the species which are UNCHANGED in going from reactants to products. A change can be a change in state. They are called SPECTATOR IONS.

Step 5: The remaining species (the ones that have changed) are the ones involved in the ionic equation. Rewrite the equation showing ONLY the species involved in the reaction.

Question 15

What are the charges of the different element groups?

Answer 15

1 -> 1+
2 -> 2+
3 -> 3+
5 -> 3-
6 -> 2-
7 -> 1-
0 -> 0