Unit II: Atoms and The Periodic Table

The Periodic Table

EPISODE IIIIIIII

PERIODIC HOPE

UNTIL NOW.

In the dark days before the

periodic table many rebel chemists

tried in vain to organize the

intergalactic elements

DmitriDmitri

History of the Periodic Table

Check out my original periodic table!

Mendeleev’s Periodic Table

Produced a table based on atomic weights but arranged 'periodically' with elements with similar properties under each other.

Mendeleev’s Periodic Table

Gaps were left for elements that were unknown at that time and their properties predicted (the elements were gallium, scandium and germanium).

The order of elements was re-arranged if their properties dictated it, eg, tellerium is heavier than iodine but comes before it in the Periodic Table.

Modern Periodic Table

Organized according to mass number rather than atomic masses

This solved the “mass discrepancy” issue with certain elements where different isotopic abundances caused masses to be out of order E.g. Ar and KCo and NiTe and I

Periodic Table – Periods

ROWS

Periodic Table - Groups

FA

MIL

IES

States of Elements

Yellow = solid (s)

Purple = gas (g)

Red

= liquid (l)

Periodic Table Some Metals

Alkali Metals

Alkali Metals

Li, Na, K, Rb, Cs, Fr These atoms each have one electron

in their valence energy level They lose one electron to form a +1

ion Most active metals on the periodic

table So reactive that they are never found

as free elements

Periodic Table Some Metals

Alkaline Earth Metals

Alkaline Earth Metals

Be, Mg, Ca, Sr, Ba, Ra

The atoms each have two electrons in their valence energy level

They lose two electrons to form +2 ion

Periodic Table Transition Metals

Periodic Table Transition Metals

Periodic Table Transition Metals

Periodic TableHalogens

Halogens

Halogens

F, Cl, Br, I, At The atoms each have seven electrons

in their valence energy level They gain one electron to form a -1

ion These elements are the most reactive

non-metals

Periodic TableNoble Gases

Periodic TableNoble Gases

He, Ne, Ar, Kr, Xe, Rn Filled valence energy

levels Do not easily combine

with other atoms to form compounds

Ar – most common noble gases ~ .93% air

STABLE – NON REACTIVE

Metals

shiny and solid at room temperature

Exception Mercury [only liquid]

Conduct heat and electricity

Tooled into sheets and wires [malleable and ductile]

Metals

Heavy Metals

to any metallic chemical element that is dense and is toxic or poisonous at low concentrations 

mercury (Hg), cadmium (Cd), arsenic (As), chromium (Cr), thallium (Tl), and lead (Pb).

Non-Metals

Generally gases or dull, brittle solids at room temperature

Bromine is the only liquid

Conduct heat and electricity poorly

Non-Metals

Metalloids=Semiconductors

Elements that have properties of both non-metals and metals

Eg. B, Si, Ge, As, Sb, Te

Important semi-conductors

Semiconductors

Nonmetal having an electrical conductivity with increasing with temperature

Silicon circuits in computers & electronics, solar photovoltaic cells

Trends in Metallic Properties

Metallic properties increase going from right to left

Metallic properties increase going down the periodic table

Metallic properties increases as you move from right to left.

Metallic prop

erties increases as you move dow

n each column

.

Trends in Metallic Properties

Bohr Models

Diagram showing the number of protons and electrons in an atom or ion

Can also include number of neutrons

First Orbit Second Orbit

Third Orbit

Maximum number of electrons 2 8 8

Bohr Model

Bohr Model

Bohr Model Patterns

Chemical families on the periodic table have the samenumber of valence electrons

Bohr Model Patterns

Elements in the same period have the same number of shells

Period number indicates the number of electron shells

Hebden

Do In-Class Activity on Trends on the Periodic Table