Question

snc2p chemistry

1. the ______ of an element represents one atom of that element.

• zn = ____ atom of zinc

1. a ______ is a number written at the lower right - corner behind the symbol of an element.

• it shows how many ______ of an element exist in a molecule.
• f₂ = ____ atoms of fluorine in a molecule

1. a subscript outside a ______ multiplies all the elements inside the brackets.

ca(oh)₂ = __ calcium atom, oxygen atoms, __ hydrogen atoms
ba(po₄)₂ = __ barium atoms, phosphorus atoms, __ oxygen atoms

1. a ____ is a number written in front of a chemical symbol. it indicates the number of ____ of that element (used for balancing chemical equations).

• 3 co = ____ cobalt atoms

1. ____ can also be written in front of a __ to indicate the number of ____ of a compound.

3 h₂o =
____ water molecules
atom count: ____
2 caso₄ =
____ molecules of calcium sulphate
atom count: ____
4 cu(no₃)₂ =
____ molecules of copper (ii) nitrate
atom count: ____

Explanation:

1. The symbol of an element represents one atom of that element. So for Zn, it represents 1 atom of zinc.
2. A sub - script is a number written at the lower right corner behind the symbol of an element. It shows how many atoms of an element exist in a molecule. For F₂, there are 2 atoms of fluorine in a molecule.
3. A subscript outside a bracket multiplies all the elements inside the brackets. In Ca(OH)₂, there is 1 calcium atom, 2 oxygen atoms and 2 hydrogen atoms. In Ba(PO₄)₂, there is 1 barium atom, 2 phosphorus atoms and 8 oxygen atoms.
4. A coefficient is a number written in front of a chemical symbol. It indicates the number of atoms of that element. For 3Co, there are 3 cobalt atoms.
5. A coefficient can also be written in front of a chemical formula to indicate the number of molecules of a compound. For 3H₂O, there are 3 water molecules, with a total of 6 hydrogen atoms and 3 oxygen atoms. For 2CaSO₄, there are 2 molecules of calcium sulphate, with 2 calcium atoms, 2 sulphur atoms and 8 oxygen atoms. For 4Cu(NO₃)₂, there are 4 molecules of copper (II) nitrate, with 4 copper atoms, 8 nitrogen atoms and 24 oxygen atoms.

Answer:

1. symbol; 1
2. sub - script; atoms; 2
3. bracket; 1; 2; 2; 1; 2; 8
4. coefficient; atoms; 3
5. coefficient; chemical formula; molecules; 3; 6 hydrogen and 3 oxygen; 2; 2 calcium, 2 sulphur and 8 oxygen; 4; 4 copper, 8 nitrogen and 24 oxygen