Elements & Compounds
Name the chemical symbol for:
a) phosphorous
b) sodium
c) lithium
d) calcium
a) P
b) Na
c) Li
d) Ca
Draw and describe the arrangement of particles in a SOLID.
Particles closely packed in a regular arrangement;
they vibrate in fixed positions; strong forces hold them together.
What is one sign that a chemical reaction has occurred?
Gas production, precipitate, temperature change, permanent colour change, light or sound.
Write the word equation for hydrogen gas reacting with oxygen gas.
Bonus 100-200 points: What type(s) of reaction is this? Explain your answer.
Hydrogen + Oxygen → Water
Bonus: This is a combustion reaction because hydrogen reacts with oxygen and releases energy.
It is also an exothermic reaction because energy is released as heat and light.
What is the difference between a physical property and a chemical property?
Physical properties can be observed without changing the substance.
Chemical properties describe how a substance reacts to form new substances.
Name the chemical symbol for:
a) silicon
b) magnesium
c) iron
d) copper
a) Si
b) Mg
c) Fe
d) Cu
Name THREE assumptions the particle model makes about all matter.
- All matter is made of tiny particles
- Particles are always moving
- There are spaces between particles
- Particles attract each other
- Heating particles, gives them more energy
A blue liquid is cooled and becomes a blue solid.
Identify whether this is a chemical or physical change? Explain your answer.
Only the state changed; no new substance formed; colour remained the same.
Why must a chemical equation contain the same number of each type of atom on both sides?
Atoms cannot be created or destroyed during a chemical reaction, so the same atoms must be present before and after the reaction. They are simply rearranged into new substances.
Name THREE chemical properties and THREE physical properties of a substance.
Chemical: flammability, toxicity, corrosion/reactivity, sensitivity to light.
Physical: colour, hardness, density, melting point, boiling point, conductivity
Name the chemical symbol for:
a) tin
b) silver
c) potassium
d) lead
a) Sn
b) Ag
c) K
d) Pb
Why can liquids flow but solids cannot? Use the particle model in your answer.
In liquids, particles are close together but can move past each other because the forces are weaker.
In solids, particles are held in fixed positions and can only vibrate.
A student mixes two clear solutions together. A white solid immediately forms and the beaker becomes slightly warmer.
Is this a physical or chemical change?
Give two pieces of evidence that support your answer.
A chemical change.
Formation of a precipitate (solid)
Temperature increase (exothermic)
A scientist observes 2 reactions:
Reaction A causes the temperature of the surroundings to increase.
Reaction B causes the temperature of the surroundings to decrease.
Classify each reaction and explain your reasoning using energy transfer.
Bonus 100 points: Name a reaction that requires a continuous input of sunlight to occur.
Reaction A is exothermic because energy is released to the surroundings, causing the temperature to increase.
Reaction B is endothermic because energy is absorbed from the surroundings, causing the temperature to decrease.
Bonus: Photosynthesis
Endothermic reaction because plants absorb light energy from the Sun to convert carbon dioxide and water into glucose and oxygen.
Why are diamond-tipped drill bits used to cut concrete and rock?
Diamond is extremely hard, allowing it to cut through other materials without wearing away quickly.
Name the chemical formula for:
a) sodium chloride
b) hydrochloric acid
c) methane
d) mercury
a) NaCl
b) HCl
c) CH4
d) Hg
Explain at the particle level what happens when a substance is heated.
When heated, particles:
Chemical or Physical change? Explain your answer.
a) A glow stick begins glowing after it is snapped.
b) Salt dissolving in water
a) Chemical Change - A chemical reaction occurs and releases energy as light.
b) Physical change. No new substance is formed — Can be reversed by evaporation.
Iron is left outside and develops a reddish-brown coating.
a) What type of reaction is this?
b) Write the word equation for this reaction.
Bonus 100 points: Write the balanced chemical formula equation.
a) Corrosion (rusting)
b) Iron + oxygen → iron oxide
Iron + oxygen + water → iron oxide
Bonus Points: 4Fe + 3O2 → 2Fe2O3
Why is stainless steel commonly used in kitchen sinks?
It is corrosion resistant.
It does not rust easily when exposed to water and cleaning products, making it suitable for long-term use in wet environments.
Name the chemical formula for:
a) sulfuric acid
b) phosphoric acid
c) nitric acid
d) carbonic acid
a) H₂SO₄
b) H₃PO₄
c) HNO₃
d) H₂CO₃
A gas is heated in a sealed container. Use the particle model to explain why pressure increases.
Particles gain kinetic energy, move faster and collide with the container walls more often and with greater force.
Compare the reversibility of physical and chemical changes.
In physical changes, particles may change their arrangement, spacing or state, but the substance remains the same, so the change can often be reversed.
In chemical changes, bonds between atoms are broken and new bonds are formed, creating new substances with different properties. This makes chemical changes difficult to reverse.
Balance the following equation:
C₃H₈ + O₂ → CO₂ + H₂O
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
Propane
Engineers are choosing a material for an outdoor bridge.
Identify one chemical property and one physical property the material should have.
Explain why each property is important for this use.
Chemical property: Corrosion resistance
Physical property: High strength