Ions

Ions

Ions

• An ion is an atom that has gained or lost an electron or electrons.

• An atom that loses an electron or electrons will have more protons than electrons, it will become an ion with a positive charge.

• An atom that gains an electron or electrons will have more electrons than protons, it will become an ion with a negative charge.

• Atoms that have a charge can only gain or lose electrons they cannot gain or lose protons.

Multiple Choice

An ion is an atom that has gained or lost _______.

• protons

• neutrons

• electrons

Multiple Choice

An atom that gains electrons will have a ___ charge.

• negative

• positive

Multiple Choice

An atom that loses electrons has a ____ charge.

• negative

• positive

Cations and Anions

• Cations- pronounced cat-ion- is an ion with a positive charge (it will be an ion that lost electrons). It has more protons than electrons.

• Anions- pronounced an-ion- is an ion with a negative charge (it will be an ion that gained electrons). It has more electrons than protons.

Multiple Choice

Cations have a positive charge, which means they have _____ electrons.

• gained

• lost

Multiple Choice

An ion that has negative charge has gained electrons, it is called a(n)

• anion

• cation

Valence Electrons and Ions

• Atoms gain or lose electrons from the highest energy level.

• The atoms in the highest energy level are called valence electrons.

• To find the number of valence electrons in an atom of a representative element, simply look at its representative group number.

• Elements in group 5A like nitrogen have 5 valence electrons.

Multiple Choice

Valence electrons are atoms of the outer most energy level, there is a maximum number of eight.

• True

• False

Multiple Choice

How many valence electrons does an atom of silicon have?

• 3

• 4

• 5

• 6

Multiple Choice

Be, Mg, and Ca have ___ valence electrons.

• 1

• 2

• 3

• 4

Octet Rule

• The octet rule determines if an atom will gain or lose electrons.

• The outer level of an atom has eight electrons.

• An atom will gain or lose electrons to have a full outer energy level.

• Atoms of metals tend to lose their valence electrons. Nonmetals tend to gain or share electrons to achieve a full octet.

Multiple Choice

Atoms will gain or lose electrons in order to have a full outer energy level this is called the _____ rule.

• valence

• cation

• octet

• anion

Will an atom gain or lose an electron?

• Atoms in group 1A, 2A, and 3A lose electrons. Remember the atom want a full outer energy level.

• For atoms that lose electrons, they empty the outer most energy level.

• For groups 1A - 3A - atoms lose electrons forming a positive ion.

• For groups 5A - 7A - atoms gain electrons forming a negative ion.

• For group 4A- atoms can gain or lose electrons forming a positive or negative ion.

Multiple Choice

Group 2A will _____ electrons, forming an ion with a positive charge.

• gain

• lose

Multiple Choice

Group 7A elements _____ electrons, forming a negative charge.

• gain

• lose

Elements that lose electrons form cations

• Atoms that lose electrons have more protons than electrons, the ion that forms has a positive charge and is a cation.

• They are part of representative groups 1A - 4A.

• The group number is the same as the charge.

• For example magnesium is in group 2A, it will lose 2 electrons. It will have 12 protons and 10 electrons so the charge of a magnesium ion is +2.

Multiple Choice

What is the charge on an ion of sodium (Na)?

• +1

• +2

• +3

• +4

Multiple Choice

Aluminum forms an ion with +3 charge, what group is it in?

• 1A

• 2A

• 3A

• 4A

Elements that gain electrons form anions

• Nonmetals tend to gain or share electrons forming negative ions or anions.

• When an atom gains an electron or electrons it forms an ion with more electrons than protons. It forms a negative ion (an anion).

• To determine the charge of a negative ion (anion) subtract the representative group number from 8.

• Example- Sulfur is in group 6A. Subtract the group number from 8. (8-6=2). Sulfur forms an anion with a charge of -2.

Multiple Choice

An atom of Br will form an anion. What will the charge of the anion be?

• +1

• +2

• -1

• -2

Multiple Choice

Phosphorous forms an anion with a charge of -3 what representative group is it part of?

• 3A

• 4A

• 5A

• 6A

Writing Ions with symbols.

• An ion is written with the symbol and the charge.

• Examples of cations (positive ions) - K⁺¹, Sr⁺², B⁺³

• Examples of anions (negative ions) - F^-1, O^-2, N^-3