TOUR OF THE PERIODIC TABLE 4 2 Main

TOUR OF THE PERIODIC TABLE 4. 2

Main Group Elements A • The main group elements are group A elements: 1 -8, and they do not include the transition metals or the rare earth elements (lanthanides and the actinides).

Following the Octet Rule • Almost all elements will want to have a full outer shell. This is the most stable electron configuration for an element. • The outer shell will have 2 electrons for period 1, or 8 electrons for periods 2 -7.

Exception • Group 8, the noble gases, have a full outer shell (Helium = 2 electrons, all others have 8 electrons) and so they will not form ions.

Octet Rules • The other elements will either lose or gain electrons to have a full outer shell. How many they will lose or gain depends on how close they are to having 8 valence electrons. 1. Groups 1 – 3 will lose their valence electrons so they can have a full outer shell by exposing the shell underneath. It is less energy to lose than to gain. • Exception is H, which is not a group 1 element anyways – can gain 1 electron to become more stable with a full outer shell of 2 electrons or less stable to become the H+ ion.

Octet Rules Groups 5 -7 will gain electrons to obtain a full outer shell. It is less energy to gain a fewer number of electrons than to lose. 2. 3. Group 4 will either gain or lose electrons to obtain a full outer shell. 4. Group 8 – Noble Gasses - will neither gain or lose electrons. They are already stable.

Determine the ion charge for a given element • Also write the symbol with the superscript and charge: 1. For Na: how many valence electrons? How many electrons will it lose or gain? 2. For N: how many valence electrons? How many electrons will it lose or gain? 3. For Ne: how many valence electrons? How many will it lose or gain? 4. For C: how many valence electrons? How many will it lose or gain electrons?

Answers Na has 1 valence electron, it will lose 1 and become Na+ • 2. N has 5 valence electrons, it will gain 3 and become N 3 • 3. Ne has 8 valence electrons, it will not gain or lose electrons, Ne • 4. C can gain or lose 4 electrons, either C 4+ or C 4 • 1.

Most Reactive Groups • An element becomes more reactive the closer they get to achieving 8 valence electrons. So Groups 1 and 7 are the most reactive groups. Because they have only one electron to move.

Reactivity Depends on Electrons • The Alkali metals (very reactive) = group 1 • The Alkaline metals (less reactive) = group 2 • Semi-metals, Metalloids, Semi-conductors = Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium (not that reactive) have both properties of metals and non-metals. • The halogens (very reactive non-metals) = 7 • The noble gases (stable, non-reactive nonmetals) = 8

Transition Metals, Lanthanides and Actinides • Transition metals are in the middle of the periodic table and the Lanthanides and Actinides are the last 2 rows that are separated from the periodic table.

Hydrogen • Hydrogen is in a class by itself because it has different properties when compared to the other elements. So it is not a part of the group 1 Alkali metals or any other group. It is very reactive because it wants 1 more electron to have 2 valence electrons in its outer shell = full outer shell. It usually does this by sharing 2 electrons between 2 hydrogen atoms and forming diatomic hydrogen, H 2.

The Staircase separates Metals and the Non-metals • Metals make up most of the Periodic Table. The staircase that is on the right side of the table divides the metals from the nonmetals. • Metals are on the left side of the staircase and non-metals are on the right side of the staircase. • Know that semi-metals hug the staircase.

Classwork • For elements 1 -20: • 1. Write how many valence electrons it has when neutral • 2. Write how many electrons it will gain or lose to get 8 valence electrons or a full outer shell. • 3. Write the element symbol and charge • Octet Rule: Groups 1 -3 lose, Groups 5 -7 gain, Group 8 does nothing, Group 4 can lose or gain Examples: 1. H : 1 valence electron, gain 1 to have full outer shell, H- or can lose one electron H+

• 2. He = 2 valence electrons, will do nothing, He • 3. Li = 1 valence electron, will lose 1 electron, Li+ • 4. Be = 2 valence electrons, will lose 2 electrons, Be+2 • 5. B = 3 valence electrons, will lose 3 electrons, B+3 • 6. C = 4 valence electrons, can lose or gain 4, C+4, C-4 • 7. N = 5 valence electrons, will gain 3 electrons, N-3 • 8. O = 6 valence electrons, will gain 2 electrons, O-2 • 9. F = 7 valence electrons, will gain 1 electron, F • 10. Ne = 8 valence electrons, it will do nothing, Ne

• 11. Na = 1 valence electron, lose 1 e, Na+ • 12. Mg = 2 valence electrons, lose 2 e, Mg+2 • 13. Al = 3 valence electrons, lose 3 e, Al+3 • 14. Si = 4 valence electrons, lose or gain 4, Si+4, Si-4 • 15. P = 5 valence electrons, gain 3, P-3 • 16. S = 6 valence electrons, gain 2, S-2 • 17. Cl = 7 valence electrons, gain 1, Cl • 18. Ar = 8 valence electrons, does nothing, Ar • 19. K = 1 valence electrons, lose 1 e, K+ • 20. Ca = 2 valence electrons, lose 2 e, Ca+2

• Li = 1 valence electron, lose 1 electron to have 2 valence electrons. • Be ?

• Be = 2 valence electrons, lose 2 electrons to have 2 • C?

• C = 4 valence electrons, can gain 4 to have 8 or lose 4 electrons to have 2 in the bottom shell. • B=?

• B = 3 valence electrons, will lose 3 to get 2 in the bottom shell.