Grade 7 · Science · Unit 2 of 6
Atoms & Elements
Elements, compounds and chemical symbols
What your child practises
Elements versus compounds and mixtures, chemical symbols (H, O, Na, Cl, Fe, Au…), counting atoms in formulas like H₂O and C₆H₁₂O₆, metals and non-metals, and the basics of the periodic table.
NWT Curriculum learning standard: Elements consist of one type of atom; compounds; chemical symbols; metals and non-metals; the periodic table
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
What makes atoms of one element different from atoms of another element?
- how fast they move
- the temperature of the room
- the number of protons in the nucleus
- their colour
the number of protons in the nucleus
Hint: Every hydrogen atom has 1 proton; every carbon atom has 6. That number is the atomic number.
Question 2
How many different elements are in C₃H₈ (propane)?
C₃H₈propaneanswer box
2
Hint: Each capital letter starts a new element symbol. Count the different symbols, not the small numbers.
Question 3
Elements in the same column (group) of the periodic table…
- have similar chemical properties
- were all discovered in the same year
- are all gases
- all have the same mass
have similar chemical properties
Hint: Groups are like families: sodium and potassium, in the same group, both react strongly with water.
Question 4
What is the chemical symbol for calcium?
⚛️calcium- C
- Cm
- Ca
- Cl
Ca
Hint: Most symbols are the first one or two letters of the name (O for oxygen, Ca for calcium). Some come from Latin names: Na (natrium) for sodium, Fe (ferrum) for iron, Au (aurum) for gold, Ag (argentum) for silver, K (kalium) for potassium, Pb (plumbum) for lead, Hg (hydrargyrum) for mercury, Sn (stannum) for tin.
Question 5
Element, compound or mixture? Sort each substance.
Sort into: ⚛️ element · 🧪 compound · 🥣 mixture
- 🥗fruit salad
- 💧water (H₂O)
- 🟡gold (Au)
- 🪴garden soil
- 🧂table salt (NaCl)
- 🎈helium (He)
⚛️ element: gold (Au), helium (He) · 🧪 compound: water (H₂O), table salt (NaCl) · 🥣 mixture: fruit salad, garden soil
Hint: An element has only one kind of atom. A compound has different elements chemically joined in a fixed ratio. A mixture is substances mixed together but not chemically joined.
Question 6
What is an element?
⚛️- Any liquid that conducts electricity
- A mixture that can be separated by filtering
- A substance made of two or more different kinds of atoms joined together
- A pure substance made of only one type of atom
A pure substance made of only one type of atom
Hint: Gold contains only gold atoms; oxygen contains only oxygen atoms. That's what makes them elements.