chemical bonding

Chemical Bonding : 

Chemical Bonding

What are Valence Electrons? : 

What are Valence Electrons? Electrons that are in the outer energy level of an atom. Example: Potassium (K) has 19 electrons that are found throughout 4 energy levels. Potassium has only 1 electron in it’s 4th energy level which would be its only valence electron. Example: Bromine (Br) has 35 electrons that are also found throughout 4 energy levels. However, where Potassium has only 1 valence electron, Bromine has 7 electrons in its 4th energy level giving it 7 valence electrons.

Slide 3: 

The Periodic Table (valence electrons by group) 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 These numbers represent the number of valence electrons that each atom in the group has in it’s outer energy level These numbers not only represent the periods of the Periodic Table, but they also represent the number of valence electrons that each atom in the group has in it’s outer energy level

IONS : 

IONS IONS are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom foms a CATION with a positive charge Adding an electron to an atom forms an ANION with a negative charge. To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2 Na Ca I O

Forming Cations & Anions : 

Forming Cations & Anions A CATION forms when an atom loses one or more electrons. An ANION forms when an atom gains one or more electrons Mg --> Mg2+ + 2 e- F + e- --> F-

PREDICTING ION CHARGES : 

PREDICTING ION CHARGES In general metals (Mg) lose electrons ---> cations nonmetals (F) gain electrons ---> anions

Charges on Common Ions : 

Charges on Common Ions By losing or gaining electrons, atom has same number of e-’s as nearest Group 8 atom. +3

The Rule of 8 : 

The Rule of 8 The Rule of 8 says that atoms tend to gain, lose or share electrons so as they have or seem to have eight electrons in their valence electron shell. Many atoms lose or gain electrons to obtain an electron configuration like that of the nearest Noble Gas. In general, the Rule of 8 works for most metals and nonmetals, but not for the transition elements.

Types of Chemical Bonds : 

Types of Chemical Bonds Ionic Bond Formed between a positively charged atom and a negatively charged atom Formed by a transfer of electrons (givers and takers) typically involves a metal with a nonmetal

Covalent Bond : 

Covalent Bond Exists when electrons are shared by two non-metallic atoms The animation shows what happens in the formation of a covalent bond.  When each chlorine atom shares its unpaired electron, both atoms are tricked into thinking each has a full valence of eight electrons.