The Periodic Table Unit 2 – Lecture 4

Periodic Table Describes trends in physical and chemical properties number of electrons, protons, neutrons charge reactivity type of element

Properties Chemical Properties are based on the number of valence e-s Elements in same group/family elements have same # of valence e-s group 1 = 1, group 2 = 2 group 13-18, drop the “1” in front of the group # ex: 13 = 3, 14 = 4 Helium has 2 Groups 3-12 use a different set of electrons, so it doesn’t follow the typical pattern

Charge Recall: “Octet Rule” atoms will gain, lose, or share e-s to become chemically stable [8 e-s in valence shell] PT indicates charge by groups as well again, groups 3-12 are left out of this

Charge – cont’d Groups 1 = +1, 2 = +2, 13 = +3 want to lose electrons

Charge – cont’d Group 14 = +/- 4  will gain or lose electrons equally gain/loss depends on what it bonds to

Charge – cont’d Groups 15 = -3, 16 = -2, 17 = -1, 18 = 0 want to gain electrons

Charge – cont’d group 18 will not gain, lose, or share e-s [bc they have 8 e-s anyway]

Charge – cont’d Which is the more “positive term: CAT? or ONION?

Charge – cont’d Useful chemistry terms: cation – positively charged atom mostly metals anion – negatively charged atom mostly non-metals

Oxidation # Oxidation Number – the number of e-s an atom will gain, lose, or share in order to become stable basically the same as the charge on the PT again, leave out groups 3-12 GROUP number indicates the number of outer-shell e-s groups 1, 2, then groups 13-18 (except He) Always 4 or less [+ or -]

Oxidation/Charge Numbers +1 +2 ----------------------------------------- +3 +/-4 -3 -2 -1 0

In order to become stable… …an Oxygen atom an will… lose 6 e-s gain 6 e-s lose 2 e-s gain 2 e-s OR none of the above …a Calcium atom will… lose 6 e-s gain 6 e-s lose 2 e-s gain 2 e-s OR none of the above … a Sodium atom will… lose 7 e-s gain 7 e-s lose 1 e-s, gain 1 e- OR none of the above

In order to become stable… …a Bromine atom an will… lose 7 e-s gain 7 e-s lose 1 e-s gain 1 e-s OR none of the above …a Xenon atom will… lose 8 e-s gain 8 e-s lose 0 e-s gain 0 e-s OR none of the above

The Periodic Table Periodic = in a regular, repeating fashion Early designs of the PT were based on use, physical properties, and even spelling.

Mendeleev’s Contributions Organized first working Periodic Table according to chemical properties and atomic mass Left gaps for undiscovered elements He was able to predict many properties of these undiscovered elements based on their location

Periodic Table – cont’d column = group/family elements in a family have the same chemical properties [valence e-s, reactivity…] row = period properties of elements repeat across a period [size of atom, ease of losing e-s]

Group 1 Alkali Metals Highly reactive metals 2ectron

Group 2 Alkaline Earth Metals Reactive metals Have two outer shell electrons

Groups 3-12 Transition Metals “normal” metals have one to ten outer shell electrons

Groups 3-12 cont’d Lanthanide (57-71) & Actinide (89-103) series can be considered to be “inner” transition metals.

Metals vs. Non-Metals Metals Non-Metals Location left of the “stairs” right of the “stairs Appearance lustrous waxy or dull “Shape-ability” malleable & ductile brittle Conductivity [heat & electricity] very good poor - better as insulators Physical State solid at room temp [except Hg] gas or solid at room temperature [except Br] Charge typically cations typically anions

Metalloids May have properties of metals and nonmetals Located on the stair-step Some are semiconductors: they only conduct electricity under certain conditions This makes metalloids excellent switches for computers

Group 17 Halogens Means “Salt Former” Highly reactive nonmetals Have seven outer shell electrons

Group 18 Noble Gases Completely unreactive nonmetals Will not bond with any atom Have a full outer shell of electrons Eight for all but Helium He has two outer shell electrons

Practice Which group is known as the Halogens? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 Which group has a stable number of outer shell electrons? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 What is the group name for Group 2? Alkaline Earth Metals, Alkali Metals, Halogens, Transition Metals, Noble Gases

Practice Which group is known as the Transition Metals? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 Which group has two outer shell electrons? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 What is the group name for Group 18? Alkaline Earth Metals, Alkali Metals, Halogens, Transition Metals, Noble Gases

Practice Elements of which group are known as the Alkali Metals? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 Elements of which group have a variable number of outer shell electrons?

Practice Which scientist arranged elements in a working Periodic Table? Galileo, Aristotle, Al-Gebbri, Mendeleev Which property of elements is the basis for arrangement in the Periodic Table? Atomic Mass, Boiling Point, Number of Neutrons, Chemical Properties Which subatomic particle determines the chemical properties of an element? Protons, Neutrons, Electrons, Quarks

Practice Vertical columns on the Periodic Table are Groups, Rows, Periods, Clans How many valence electrons would Sulfur have? (Group 16) 2, 6, 8, 16, 32 Nonmetals are located To the left of the stair-step, On the stair-step, To the right of the stair-step, At the very bottom

Problems Which group on the Periodic Table are known as “Halogens”? Group 1, Group 2, Groups 3 – 12, Group 17, Group 18 Ductile, Malleable, & solid at room temp. Metalloids, Nonmetals, Metals, Yoda Usually gas at room temp., brittle, dull or waxy Metalloids, Metals, Nonmetals, Your HAIR!

Electronegativity ability to hold onto outer valence e-s high electronegativity = tightly held e-s low electronegativity = loosely held e-s

Electronegativity – cont’d increases as you go from left to right across a period. easier to give away a few [like those to the L] than to steal many [like those on the R]

Electronegativity – cont’d decreases as you go down a group. “every electron matters” – those with many can afford to lose some, those with little can’t electrons shield the nucleons [protons & neutrons] the farther out electrons are from the nucleus, the less tightly held they are [away from + charge]

Reactivity how likely or vigorously an element reacts with others Metals: decreases as you go from left to right across a period. reactivity increases as you go down a group . Why? It’s easier for those elements to get rid of electrons.

Reactivity – cont’d Non-Metals: increases as you go from the left to the right across a period. decreases as you go down the group. Why? It’s easier for those elements to steal electrons.

Atomic Radius decreases as you go from left to right across a period. attractive forces btw opposite charges (electrons outside / protons inside) cause cloud to be 'sucked' together a little tighter.

Atomic Radius – cont’d increases as you go down a group. Why? Large jump in size of nucleus (p+s + n0s) each time you move from period to period down a group. also, new E levels added when moving down periods

Alkali metals (not H) (1) Inner transition (1) Gs and Ls correct (1) Transition metals (1) Metalloids (1) Halogens (1) IA, IIA, etc. labels (1) Noble gasses (1) Alkali metals (not H) (1) Inner transition (1) Alkaline earth metals (1) Legend filled in (1) VIIA VIA VA IVA IIIA IIA IA G L Marks: 10 Total: 20