4-FormulaAAndReactingQuantities

Question 1

How do you name a compound?

Answer 1

Metals always come first
If the compound only contains 2 elements, the end changes to IDE
If the compound contains 2 or more elements plus oxygen, the end changes to ADE

Question 2

How do you make a word equation?

Answer 2

Reactants — Products
Arrow always means produced
If a chemical has 2 parts to its name, they go one under the other
Descriptions such as powder, metal, gas, dilute and solution (anything that isn’t part of the compound name) isn’t included

Question 3

How do you count atoms?

Answer 3

Subscripts: refer to the atoms behind them till the next subscript appears
Coefficient: big number which refers to all atoms in front of it, multiply coefficients and subscripts
Parenthesis: brackets, the subscript only refers to anything in the brackets

Question 4

What information does the chemical formula give in covalent molecular substances, covalent networks and ionic compounds?

Answer 4

Covalent molecular substances: the chemical formula of a covalent molecular substance gives the number of each type of atom present
Covalent network: the formula of a covalent network gives the simplest ratio of each type of atom
Ionic compounds: the formula of an ionic compound gives the simplest ratio of each type of ion

Question 5

When charges and the number of atoms/ions are in chemical formula, should they be superscript or subscript?

Answer 5

Charges must be superscript
The numner of each atom/ion must be subscript

Question 6

What are the 5 ways to express chemical formula?

Answer 6

-from prefixes
-using SVSDF
-using roman numerals
-containing group ions
-ionic formula

Question 7

Describe prefixes

Answer 7

They give the number of atoms of that element present
Mono = 1 atom
Di = 2
Tri = 3
Tetra = 4
Penta = 5
Hexa = 6
Hepta = 7
Octa = 8
Non = 9
Deca = 10

Question 8

Describe SVSDF

Answer 8

Should not be used if a prefix is present
Stands for:
Symbols
Valency
Swap
Divide
Formula

Question 9

What is valency?

Answer 9

The valency of a substance is the number of bonds an atom will form
You know how many bonds an atom will form by looking at its outer energy level. The number is how many electrons are needed to be gained or last to make it stable

Question 10

What are the results of oxygen, hydrogen and carbon dioxide in gas tests?

Answer 10

Oxygen- relights a glowing splint
Hydrogen- burns with a pop
Carbon dioxide- turns limewater from colourless to cloudy

Question 11

Roman numerals

Answer 11

Indicate the valency of transition metals
If no Roman numeral: assume valency is 2
I-1
II-2
III-3
IV-4
V-5
VI-6

Question 12

Containing group ions

Answer 12

Valency is equal to the charge on the ion
+
Ammonium- NH
4
__
Hydroxide- OH
Don’t use the charges on p8 of booklet
Put brackets around group ions if there is more than one
SVSDF

Question 13

Ionic formula

Answer 13

Only written for ionic compounds
Metal atoms form positive ions
Non meta atoms form negative ions
Valency of the atom or group ion is the same as a charge
Both charges must be shown
Brackets around group ions if there is more than one
SVSDF

Question 14

Formula equations

Answer 14

Write down symbols
If diatomic, write symbol 2
If substance isnt an element, write formula name, if not use valency to work it out

Question 15

State symbols

Answer 15

Added to formula equations to give more information about the reactants and products
Solid (s)
Liquid (l)
Gas (g)
Aqueous (dissolved in water) (aq)

Question 16

Balanced chemical equations

Answer 16

Number of reactant atoms = number of product atoms
Check all your formulae are correct
Deal with one element at a time
Write numbers infront of the formulae
Don’t change numbers within the formula
Repeat
Balance metals first
Balance non metals (other than C, H, O)
Balance C, H then O