Bonding

Ion A charged particle created when an atom gains or loses an electron. Metals tend to lose electrons. Nonmetals tend to gain electrons.

Positive Ion It is easier for metals to lose one, two, or three electrons than to gain five, six, or seven electrons. i.e. Li has 3 protons and 3 electrons 2 electrons are in the first energy level and only 1 in the outer energy level. If 1 electron is lost, there remains 3 protons. 3 positively charged protons and only 2 negatively charged electrons leaves an ion of lithium with a positive charge.

Positive Ion 3+ e- Li Li+ 3+ e- e-

Negative Ion It is easier for nonmetals to gain one, two, or three electrons than to lose five, six, or seven electrons. i.e. F has 9 protons and 9 electrons 2 electrons are in the first energy level and 7 in the outer energy level. If 1 electron is gained, there are still 9 protons. 9 positively charged protons and 10 negatively charged electrons leaves an ion of lithium with a negative charge.

Negative Ions 9+ e- F F e- e- e- e- e- 9+ e- e- e- e-

Negative Ions 9+ e- F F F- e- e- e- e- e- 9+ e- e- e- e- e-

Ionic Bonds Ionic bonds form when two ions are held together because they are oppositely charged. As the metal loses an electron, it becomes positively charged. As the nonmetal gains an electron, it becomes negatively charged. These positive and negative ions attract together.

Covalent Bonding Covalent bonds form when two nonmetals, which tend to gain electrons, share at least one pair of electrons. One electron in the pair is typically from each atom.

Covalent Bonds F F e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- 9+ 9+ e- e- e- e- e- e- e- e-

Covalent Bonds F F e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- 9+ e- 9+ e- e- e- e- e- e- e- e-

Both Ionic & Covalent Bonds The compound made by a chemical bond is electrically neutral. The overall charge is zero. The sum of the protons equals the sum of the electrons.