Balancing Equations
What must be equal on both sides of a balanced chemical equation?
The number of atoms of each element
What type of elements usually form covalent compounds?
Non-metals
What is the name given to Group 17 elements?
Halogens
Ionic compounds usually form between what two types of elements?
A metal and a non-metal
What are the substances you start with in a chemical reaction called?
Reactants
Balance: H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
What happens to electrons when a covalent bond forms?
Electrons are shared
What is the name given to Group 18 elements?
Noble Gases
What happens to electrons when an ionic bond forms?
Electrons are transferred
What are the substances produced in a chemical reaction called?
Products
Balance: Mg + O₂ → MgO
2Mg + O₂ → 2MgO
How many atoms are present in one molecule of CO₂?
3
Why are noble gases generally unreactive?
They have a full outer electron shell
What charge does a Group 17 element usually form as an ion?
−1
Complete the word equation Methane gas (CH4) is used in gas heaters in homes all around Perth during winter. When the heater is ignited, methane combines with oxygen gas (O2) in the air to form carbon dioxide and water.
methane + oxygen --> carbon dioxide + water
Balance: N₂ + H₂ → NH₃
N₂ + 3H₂ → 2NH₃
What does the prefix di- mean in a covalent compound name?
Two
Name two Group 17 elements
Any two: fluorine, chlorine, bromine, iodine
What is the chemical formula for magnesium chloride?
MgCl₂
Which is the reactant in this word equation Al2O3 → Al + O2
Al2O3
Balance: CH₄ + O₂ → CO₂ + H₂O
CH₄ + 2O₂ → CO₂ + 2H₂O
Name the compound MgBr2
Magnesium Bromide
What happens to the reactivity of the halogens as you move down Group 17?
Reactivity decreases
What is the law of conservation of mass in a closed system?
Mass is conserved — it is not created or destroyed. The total mass of the reactants equals the total mass of the products.
Which is the product in this word equation Al2O3 → Al + O2
Al + O2