Groups continued

Atomic Number

• This refers to how many protons an atom of that element has.

• No two elements, have the same number of protons.

Bohr Model of Hydrogen Atom

Wave Model

Atomic Mass

• Atomic Mass refers to the “weight” of the atom.

• It is derived at by adding the number of protons with the number of neutrons.

HThis is a helium atom. Its atomic mass is 4 (protons plus neutrons).

What is its atomic number?

• The arrangement of elements in vertical column called Groups and horizontal rows called Periods in order of increasing proton number

• There are 18 Groups numbered 1-18 and 7 Periods numbered 1-7 in a Periodic Table.

MODERN PERIODIC TABLE

Periods

• Across the period from left to right

Proton number increasesElement become non-metallic

Sodium and water

https://www.youtube.com/watch?v=uqDWbknpiVk

Potassium and water https://www.youtube.com/watch?v=OFG4Yr7lQzw

Alkali Earth Metals

Alkaline Earth Metals

• 2nd Family • From Beryllium to Radium • Shiny, silvery-white• Somewhat reactive

Elements In Family

• Beryllium• Magnesium• Calcium• Strontium• Barium• Radium• Unbinilium

Representative Elements

and has a higher melting point than the alkali metal in the same period.

• Each alkaline earth metal is denser and harder

Alkaline Earth Metals• Next to the alkali metals are the alkaline

earth metals.

• Alkaline earth metals are reactive, but not as reactive as the alkali metals.

Group Trends

• silvery and of fairly low density• density increases down the group

Group Trends

– stronger metallic bonding than the alkali metals

• also harder and have higher melting points

Element Melting Point (°C) Hatm (kJ/mol)

Mg 649 149Ca 839 177Sr 768 164Ba 727 175

General Properties

They are metalsThey are good conductors of heat and electricityTheir compounds are all white or colourlessIn all compounds they have an oxidation number

of +2They are called alkaline earth metals because

their oxides and hydroxides are basicThey react with acids to produce hydrogen

Uses

• Beryllium is used in nuclear applications• http://www.periodicvideos.com/nyt/videos/0

04.htm

Radium is used to treat cancer• Calcium is necessary for strong bones

TRANSITION METALSGroups in the middle

Good conductors of heat and electricity.

Some are used for jewelry.The transition metals are

able to put up to 32 electrons in their second to last shell.

Can bond with many elements in a variety of shapes.

Where are the transition metals?The transition metals are the block of elements located between group 2 and group 3 of the periodic table.

Ac Rf Db Sg Bh Hs Mt Ds Rg

La Hf Ta W Re Os Ir Pt Au Hg

Y Zr Nb Mo Tc Ru Rh Pd Ag Cd

Sc Ti V Cr Mn Fe Co Ni Cu Zn

?

Here, the word ‘transition’ is used to mean ‘in-between’.

group 2 group 3

Why are they called the ‘typical metals’?

There are over 30 transition metals.

The transition metals are known as ‘typical’ metals. Why do you think this might be?

They include most of the metals we are familiar with and use everyday, such as iron, copper and gold.

However, there are many transition metals that are less familiar to us, because they are very rare or have few uses.

The transition metals are known as ‘typical’ metals because of their physical properties. They are:

What are the properties of the transition metals?

lustrous (bright and shiny).

high density.

good conductors of heat and electricity.

high melting and boiling points (except mercury, which is liquid at room temperature).

hard and strong.

malleable (can be bent and pressed into different shapes) and ductile (can be drawn into wires).

Comparing properties of different metals

How do the properties of transition metals compare with those of alkali metals?

are more dense. This means that in a fixed volume of metal there are more atoms of a transition metal than there are of an alkali metal.

have higher melting and boiling points – except mercury.

are harder and stronger. They cannot be cut with a knife.

Compared to the alkali metals, the transition metals:

Transition metal compounds and colour

Most transition metals form coloured compounds.

Copper (II) sulfate crystals (CuSO4.H2O) is blue – these can be turned white by heating the crystals to remove the water.

Iron (III) oxide (Fe2O3) is red/brown – when hydrated this is rust.

Iron (II) oxide (FeO2) is black.For example:

http://chemistry.about.com/video/Properties-of-Transition-Metals.htm

Groups 13 through 18

Representative Elements

• The elements in Groups 13-18 are not all solid metals like the elements of Groups 1 and 2. Infact, a single group can contain metals, nonmetals, and metalloids and have members that are solids, liquids, and gases.

Group 13, the Boron Family

BORON FAMILY

Group 3• 3 electrons in

the outer shell• Most are

metals• Boron is a

metalloid

Boron Family

• boron family -- Group 13.• This group includes the elements boron,

aluminum, gallium, indium, and thallium. • The atomic number is 5• The atomic symbol B• Melting point= 2,076◦C• Boiling point= 3,927◦C

http://www.worldofteaching.com/powerpoints/chemistry/group%2013.ppt#256,1,Group 13, the Boron Family

Group 13—The Boron Family• The elements in Group

13 are all metals except boron, which is a brittle, black metalloid.

• Without using boron in cookware the products when transferred from a heat place to a non-heated place will cause the item to crack. So using boron helps.

How does boron effect our lives?

Boron Water Solution• Baron Water Solutions'

equipment will give you soft water, which will take away spots from your dishes and hard water build-up on your faucets and appliances, which in turn will add years to your water heater, refrigerator, dishwasher and washing machine.

• Several studies say that lack of boron weakens bones, but there is no data to show that extra boron makes bones stronger. Also boron is are used in pills to help increase blood levels for post- menopausal woman.

Group 13—The Boron Family

Representative Elements

• Aluminum is used to make soft-drink cans, cookware, siding for homes, and baseball bats.

• Gallium is a solid metal, but its melting point is so low that it will melt in your hand.

• It is used to make computer chips.

CARBON FAMILY Group 4• 4 electrons in

the outer shell• Contains

metals, metalloids, and a non-metal Carbon (C)

CARBON FAMILY Group 4• 4 electrons in

the outer shell• Contains

metals, metalloids, and a non-metal Carbon (C)

NITROGEN FAMILY Group 5• 5 electrons in

the outer shell• Can share

electrons to form compounds

• Contains metals, metalloids, and non-metals

OXYGEN FAMILY Group 6• 6 electrons in

the outer shell• Contains

metals, metalloids, and non-metals

• Reactive

HalogensGroup 7• 7 electrons in

the outer shell• All are non-

metals• Very reactive

are often bonded with elements from Group 1

Noble GasesGroup 8Exist as gasesNon-metals8 electrons in the outer

shell = FullHelium (He) has only 2

electrons in the outer shell = Full

Not reactive with other elements

Rare Earth MetalsSome are

RadioactiveThe rare

earths are silver, silvery-white, or gray metals.

Conduct electricity