Chemical Bonds

Cl - Na + Basics to Bonding When atoms join they create a chemical bond. – This chemical bond: is the force that holds two atoms together. Main types of bonds – Ionic – Metallic – Covalent H H N N

Ionic Bonding Remember when we talked about how atoms will lose or gain additional electrons – These are called ions – When the positive and negative ions form a bond they create an Ionic Bond. This forms a compound.

What happens in an Ionic Bond? The sodium atom wants to give up an electron so that its outer shell is “happy” (8 VE) Chlorine wants another electron to make its outer shell “happy” (8 VE) You can gain or lose more than one VE! 1 VE 7 VE

Metallic Bonding Metals bonding with other metals In metallic bonding the electrons in the outer energy levels are not held tightly and they move freely among the metal ions.

Covalent BONDs These are bonds in which nonmetal atoms SHARE electrons. Some atoms like carbon have 4 VE and it would take too much energy to give or take 4 more electrons…so it shares.

What Happens in a Covalent Bond? The electrons moving around are attracted to the nuclei of both atoms and move back and forth between the outer energy levels of each atom.

More stuff about Covalent BONDs Sometimes atoms can share more than one electron: If it shares two sets of electrons: Double Bond If it shares three sets of electrons: Triple Bond

Even More About Covalent BONDs Atoms don’t always share electrons the same Sharing Unequally, parts of the compound are more negative Polar Covalent Sharing electrons Equally, Non-Polar Covalent

Note Quiz 1.What happens with an electron in an ionic bond? 2.What does it mean to have a polar covalent bond? 3.What properties does metallic bonding give to metals?