Reading and Writing Chemical Formulas

A boron atom has 5 protons and 2 electrons what is the charge on the boron atom?

+3

An atom of Oxygen has 6 protons and 8 electrons what is the charge on the oxygen atom?

-2

How many elements are in O2?

1 (count the number of element symbols)

How many molecules are in this chemical formula: 2Al2O3

2 ( we determine this by looking at the coefficient)

How many Oxygen atoms are in this chemical formula: 2H2O

2 (to find this number we multiple the coefficient 2 times the subcript which is implied as 1)

Write an chemical formula for two molecules that contain two Irons (Fe), and three Oxygens (O).

2Fe2O3 (the number of molecules goes before the chemical formula, the number of atoms goes after each elemen t)

How many different elements are in C6H12O6?

3 (count the number of element symbols)

Write a chemical formula for three molecules that contain three Hydrogen atoms (H), one Phosphorus (P), and four Oxygens (O).

3H3PO4 (the number of molecules goes before the chemical formula, the number of atoms goes after each elemen t)

How many hydrogen atoms are in this chemical formula: 2H2O

4 (to find this number we multiply the coefficient 2 and subscript 2 together)

A neutral atom of boron will have __________ electrons.

5

Ions

Atoms that have an excess or shortage of electrons compared to the number of protons in the nucleus of the atom (compare p and e)

Valence Electrons

Electrons in the outermost energy level or orbitals

Write an chemical formula for a molecule that contains two Irons (Fe), and three Oxygens (O).

Fe2O3 (the number of molecules goes before the chemical formula, the number of atoms goes after each elemen t)

Write a chemical formula for a molecule that contains three Hydrogen atoms (H), one Phosphorus (P), and four Oxygens (O).

H3PO4 (the numbers of atoms becomes the subscript for each element and follows the element symbol, if there is only one atom then you do not get a subscript it is implied as 1)

Compound

Two or more different atoms/elements chemically bonded

Subscript

Used to show the number of each atom represented (this will follow the element symbol and be written below the line, if there is only one atom of that element this will not be present and will be assumed to be one)

Coefficient

Used to show the number of molecules represented (this number comes before the chemical formula)

Molecule

smallest part of a compound which is chemically unique