Question

snc2p chemistry
name: ephi
topic 5: counting atoms

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

Explanation:

1. The chemical symbol of an element represents one atom of that element. So for Zn, it represents 1 atom of zinc.
2. A subscript 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. In F₂, the subscript 2 means there are 2 atoms of fluorine in a molecule.
3. A subscript outside a parenthesis 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 or molecules of that element (used for balancing chemical equations). For 3Co, it means 3 cobalt atoms.

Answer:

1. chemical symbol; 1
2. subscript; atoms; 2
3. parenthesis; 1; 2; 2; 1; 2; 8
4. coefficient; atoms; 3