unit 2 – lecture 4 periodic table describes trends in physical and chemical properties number of...

Unit 2 – Lecture 4

Periodic TableDescribes trends in physical and chemical

propertiesnumber of electrons, protons, neutronschargereactivitytype of element

PropertiesChemical Properties are based on the number

of valence e-sElements in same group/family elements

have same # of valence e-s group 1 = 1, group 2 = 2group 13-18, drop the “1” in front of the

group #ex: 13 = 3, 14 = 4

Helium has 2Groups 3-12 use a different set of electrons,

so it doesn’t follow the typical pattern

ChargeRecall: “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 wellagain, groups 3-12 are left out of this

Charge – cont’dGroups 1 = +1, 2 = +2, 13 = +3

want to lose electrons

Charge – cont’dGroup 14 = +/- 4 will gain or lose

electrons equallygain/loss depends on what it bonds to

Charge – cont’dGroups 15 = -3, 16 = -2, 17 = -1, 18 = 0

want to gain electrons

Charge – cont’dgroup 18 will not gain, lose, or share e-s

[bc they have 8 e-s anyway]

Charge – cont’dWhich is the more “positive term:

Charge – cont’dUseful chemistry terms:cation – positively charged atom

mostly metalsanion – 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 stablebasically the same as the charge on the PTagain, leave out groups 3-12GROUP number indicates

the number of outer-shell e-sgroups 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-sOR 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 TablePeriodic = in a regular, repeating fashion

Early designs of the PT were based on use, physical properties, and even spelling.

Mendeleev’s ContributionsOrganized first working Periodic Table

according to chemical properties and atomic mass

Left gaps for undiscovered elementsHe was able to predict many properties of

these undiscovered elements based on their location

Periodic Table – cont’dcolumn = group/family

elements in a family have the same chemical properties [valence e-s, reactivity…]row =

periodproperties

of elements repeat across a period [size of atom, ease of losing e-s]

Group 1 Alkali MetalsHighly reactive metals2ectron

Group 2Alkaline Earth MetalsReactive metalsHave two outer shell electrons

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

Groups 3-12 cont’dLanthanide (57-71) & Actinide (89-103) series

can be considered to be “inner” transition metals.

Metals vs. Non-MetalsMetals 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

MetalloidsMay have properties of metals and nonmetalsLocated on the stair-stepSome are semiconductors:

they only conduct electricity under certain conditionsThis makes metalloids

excellent switches for computers

Group 17Halogens

Means “Salt Former”Highly reactive nonmetalsHave seven outer shell electrons

Group 18Noble GasesCompletely unreactive nonmetals

Will not bond with any atomHave a full outer shell of electrons

Eight for all but HeliumHe has two outer shell electrons

PracticeWhich 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 18What 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 18Which 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 18Elements of which group have a variable

number of outer shell electrons?Group 1, Group 2, Groups 3 – 12,

Group 17, Group 18

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

PracticeVertical 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 locatedTo the left of the stair-step, On the stair-step,

To the right of the stair-step, At the very bottom

ProblemsWhich 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 waxyMetalloids, Metals, Nonmetals, Your HAIR!

Electronegativityability to hold onto outer valence e-s

high electronegativity = tightly held e-slow electronegativity = loosely held e-s

Electronegativity – cont’dincreases 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’ddecreases 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]

Reactivityhow likely or vigorously an element reacts

with othersMetals:

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’dNon-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 Radiusdecreases 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’dincreases 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)Alkaline earth metals (1)

Transition metals (1)Halogens (1)Noble gasses (1)Inner transition (1)

Gs and Ls correct (1)

Legend filled in (1)

G GGG

GG

G GGG

GG

L

L

VIIAVIAVAIVAIIIAIIAVIIAIA

Marks: 10Total: 20

Metalloids (1)IA, IIA, etc. labels (1)