Lesson 3.04

Valence Electrons and Bonding

Vocabulary Terms

• Valence Electron- an electron of an atom, located in the outermost shell.

• Bond – something that holds together. • Octet Rule/Rule of Eight - chemical rule of thumb

that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells.

• Ionic Bonding - A chemical bond that results from electrostatic attraction between positive and negative ions. It is due to transfer of electrons between a metal and a nonmetal.

Vocabulary Terms

• Covalent Bonding - A chemical bond in which electrons are shared between two atoms. The sharing of electrons between two nonmetals.

• Electronegativity - tendency for an atom to attract a pair of electrons that it shares with another atom.

• Polar Covalent Bond- a covalent bond where atoms have unequal attraction for the shared electrons.

• Non-polar Covalent Bonds – a covalent bond in which the atoms have an equal attraction to the shared electrons.

Valence Electrons

• Electrons in the outermost shell or highest energy level are called valence electrons.

Ex: Carbon – 1s2 2s2 2p2Highest energy level is second level with four

electrons(2s2, 2p2), therefore the number of valence electron for carbon is equal to 4.

Valence Electrons

Valence Electrons

Valence electrons = number of dots(Lewis Dot structure)

Ionic Bonding

Transfer of electron/s between a metal(+ion) and a nonmetal(-ion)

Ionic Bonding

• Ex: NaCl

Ionic Bonding – Let’s Practice

1) Mg + Cl

2) Al + O

Covalent Bonding

Sharing of electrons between 2 nonmetals(- ion)

Covalent Bonding

Sharing of electrons between 4 atoms of Hydrogen and 1 atom of carbon to form CH4.

Ex: CH4

Covalent Bonding- Let’s Practice

1) H + Cl

2) F + F

Polar Covalent Bond

• HF

F has a higher electronegativity than H, the atom withgreater electronegativity is able to take the electrons from the other atom making it a negative ion and the other atom as a positive ion. A Polar Covalent bond has an unevendistribution of the charge, slightly negative on one end and slightly positive on the other end.

Non Polar Covalent Bond

• H2

2 atoms of Hydrogen having the same electronegativity.Both atoms have the same strength of attraction for the electrons and are equally shared. A Non polar covalentBond have an equal attraction for the shared electrons.