1. Chapter 3: Bonding

2. What is bonding? Atoms of elements can join each other to form compounds Compounds vary greatly in the elements in them and the number of elements in them Any elements can combine together, given the right environment

3. How do atoms bond? Atoms have a certain desire for electrons The noble gases have 8 electrons in their outer shell and all other elements want this 8 electron outer shell like a noble gas To get the 8 electrons, atoms cooperate together and let each other barrow or share electrons so they can each have 8

4. What ways can they bond together? Atoms can bond by three different ways: by ionic, covalent, and metallic bonds Due to the rare cases of metallic bonds they are normally not discussed in entry level chemistry courses Today we are only dealing with ionic bonds

5. So what is an ionic bond? Ionic bonds only happen between a metal and nonmetal They occur when one atom gives another atom an electron Since opposites attract, ionic bonds are formed when one atom becomes positively charged and the other becomes negatively charged

6. How do the atoms become charged Atoms have a certain ability that allows them to take or give electrons Electrons are negatively charged particle, so when an atom has more electrons than what is shown in the periodic table, the overall atom becomes negatively charged When an atom loses electrons, there is no longer enough there to cancel out the positive protons, so the atom becomes positive They all have electron affinities which is where they want electrons

7. What does this result in and how do I know if the atoms will gain or lose electrons??? If one atom becomes positive, and one atom becomes negative, then opposites attract, and these atoms are bonded together A metal is always the positive atom in the compound A nonmetal is always the negative atom in the compound

8. How many electrons do the atoms lose? Atoms will gain or lose electrons until they have eight in their outer shell The amount main group elements lose is: Group 1A: loses 1 electron= a +1 ion Group 2A: loses 2 electrons= a +2 ion Group 6A: gains 2 electrons= a -2 ion Group 7A: gains 1 electron= a -1 ion Remember group 8 doesn’t gain or lose electrons because they have 8 outer shell electrons

9. Result A perfect example is when Na loses 1 electron and becomes Na+ ion and Cl gains that 1 electrons and becomes Cl- ion Since the atoms are of different charge they are attracted to each other and are bonded This ionic bond will only occur if the two atoms are the same number ion but a different charge