Grade 7 Atoms & Elements worksheet
from Gradelings · Name: ______________________
How to explain it
- An element has only one kind of atom. A compound has two or more elements joined chemically. A mixture is substances mixed but not joined.
- Rows of the periodic table are periods; columns are groups. Metals are on the left, non-metals on the right.
- In a formula, the small number after a symbol counts the atoms just before it.
Example: How many atoms are in one molecule of H₂O? H₂ means 2 hydrogen atoms. O with no number means 1 oxygen atom. 2 + 1 = 3. Answer: 3
Question 1
Which element is a noble gas that almost never reacts with other elements?
- iron (Fe)
- neon (Ne)
- chlorine (Cl)
- sodium (Na)
neon (Ne)
Hint: Noble gases sit in the far right column of the periodic table. They glow in signs but rarely form compounds.
Question 2
About 21% of the air is made of which element, the one we need to breathe?
🌬️- carbon
- nitrogen
- helium
- oxygen
oxygen
Hint: Air is about 78% nitrogen and 21% oxygen. Our bodies use the oxygen.
Question 3
What makes atoms of one element different from atoms of another element?
- their colour
- the number of protons in the nucleus
- the temperature of the room
- how fast they move
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 4
Element, compound or mixture? Sort each substance.
Sort into: ⚛️ element · 🧪 compound · 🥣 mixture
- 💎diamond (pure carbon, C)
- 🥗fruit salad
- 💧water (H₂O)
- 🧁baking soda (NaHCO₃)
- 🪴garden soil
- 🟡gold (Au)
⚛️ element: diamond (pure carbon, C), gold (Au) · 🧪 compound: water (H₂O), baking soda (NaHCO₃) · 🥣 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 5
How many atoms in total does the formula C₃H₈ (propane) show?
C₃H₈propaneanswer box
11
Hint: A small number after a symbol tells how many of that atom there are. A symbol with no small number means 1. Add them all up.
Question 6
What is the chemical symbol for magnesium?
⚛️magnesium- M
- Mn
- Ma
- Mg
Mg
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 7
Which of these elements is a metal?
- sulphur
- carbon
- copper
- oxygen
copper
Hint: Metals are usually shiny, bendable and good conductors. Copper is used in electrical wires.
Question 8
Which element has the chemical symbol Na?
Nachemical symbol- sodium
- nitrogen
- neon
- nickel
sodium
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 9
Which property is typical of a solid non-metal, such as sulphur?
- dull and brittle
- shiny and bendable
- a good conductor of electricity
- easy to hammer into thin sheets
dull and brittle
Hint: Non-metals are usually poor conductors, and as solids they tend to be dull and break easily.
Question 10
Which element has the chemical symbol C?
Cchemical symbol- chlorine
- calcium
- copper
- carbon
carbon
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.
Answer key
- 1. neon (Ne)
- 2. oxygen
- 3. the number of protons in the nucleus
- 4. ⚛️ element: diamond (pure carbon, C), gold (Au) · 🧪 compound: water (H₂O), baking soda (NaHCO₃) · 🥣 mixture: fruit salad, garden soil
- 5. 11
- 6. Mg
- 7. copper
- 8. sodium
- 9. dull and brittle
- 10. carbon
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