Covalent Bonding Occurs when atoms share electrons Different from ionic bonding Ionic Bond = Atoms completely transfer electrons Covalent bonding occurs when two (or more) atoms share one or more electrons

Covalent Bonding Covalent bonding occurs when two or more atoms bond together The atoms on the right side of the periodic table like to gain electrons These elements will share electrons in order to fill their valence shells

Covalent Bonding Atoms become chemically stable and neutral by sharing electrons (not losing or gaining)

Covalent Bonding Covalent bonding is best illustrated using Dot Diagrams Atomic symbol with the valence electrons shown You’ve done these before!

Covalent Bonding of Two Hydrogen Atoms H is in Group One = One valence electron in its outer/only/valence shell The most electrons in this shell is two electrons Each H atom will 'want' to pick up a second electron

Covalent Bonding of Two Hydrogen Atoms In order to pick up a second electron, hydrogen atoms will react with nearby H atoms to form the molecule H 2

Covalent Bonding of Two Hydrogen Atoms The H 2 is a combination of equally matched atoms The atoms will share each others single electron Both atoms have a full valence shell

Covalent Bonding of Two Hydrogen Atoms The two hydrogen atoms “share” their electrons Both have “two” valence electrons, so are “happy” HH

Covalent Bonding Examples Covalent Bonding Chlorine

Covalent Bonding Examples Water (H 2 O) is a covalently bonded molecule

Covalent Bonding Examples Covalent Molecule Examples WATER (H 2 O) CARBON DIOXIDE (CO 2 ) OXYGEN (O 2 ) METHANE (CH 4 )

Molecular Compounds There are seven elements that will form a covalent bond with the same type of atom. H 2 F 2 Cl 2 Br 2 I 2 N 2 O 2

Covalent Bonding Multiple Bonds: Every pair of electrons shared between two atoms is a single covalent bond Some atoms can share multiple pairs of electrons, forming multiple covalent bonds For example, oxygen (which has six valence electrons) needs two electrons to complete its valence shell When two oxygen atoms form the molecule O 2, they share two pairs of electrons, forming two covalent bonds

Polarity Non-Polar Covalent Bonds Bonds where the bonding electrons are shared equally between atoms No charge

Polarity Polar Covalent Bonds One atom attracts the electrons more than another resulting in uneven sharing Slight charge

Steps for covalent bonding problems 1. Write the symbol for each element in the molecule. 2. Create dot diagrams for each (helps to use different colors for each element) 3. Rearrange electrons to pair up electrons from each atom. 4. Draw circles to show sharing of electrons 5. Write the chemical formula for the molecule

Molecules vs Compounds TermMoleculeCompound DefinitionMore than one atom bonded together with covalent bonds. Atoms of more than one type of element are bonded together (either ionic or covalent bonds) ExamplesH 2 0, CH 4, CO 2, O 2 H 2 0, CH 4, CO 2, NaCl