Atoms and the periodic Atoms and the periodic Table Table

L/O ;- To understand the L/O ;- To understand the periodic table and its history periodic table and its history

Quick quizQuick quiz1.1. How is the modern periodic table How is the modern periodic table

arranged?arranged?

2.2. T / F most elements are metals?T / F most elements are metals?

3.3. What is the name of the group which What is the name of the group which don’t react with other elements?don’t react with other elements?

4.4. What is the name of the group 7 What is the name of the group 7 gases?gases?

5.5. What is the name of the reactive What is the name of the reactive metals?metals?

The structure of the The structure of the atomatom

ELECTRON – negative,

mass nearly nothingPROTON –

positive, same mass as neutron

(“1”)

NEUTRON – neutral,

same mass as proton

(“1”)

The Ancient Greeks used to believe that everything was made up of very small particles.

I did some experiments in 1808 that proved this and called these particles ATOMS:

Dalton

In the early 19In the early 19thth Century CenturyNew elements are being discovered everyday, but are there any patterns in the behaviour of

different elementsThey seem to make sense in order of mass

Dalton

Kerboodle animationKerboodle animation

clipbankclipbank

Dalton arranged elements in order of Dalton arranged elements in order of mass but other scientist later in the 19mass but other scientist later in the 19thth century tried to arrange the elements in century tried to arrange the elements in

the periodic table.the periodic table.

Use page 210-211 AQA Chemistry Books Use page 210-211 AQA Chemistry Books to fill in the periodic table sheetto fill in the periodic table sheet

History of the Periodic Table History of the Periodic Table

1829 - Johan D1829 - Johan Döbereiner noticed triads of öbereiner noticed triads of elements with similar properties e.g. elements with similar properties e.g.

- Cl, B, I- Cl, B, I - Ca, Sr, Ba- Ca, Sr, Ba - S, Se, Te- S, Se, Te

1862 – Chancourois spotted similarities between 1862 – Chancourois spotted similarities between every 8every 8thth Element but didn’t publish his ideas Element but didn’t publish his ideas

1863 – John Newlands put the elements in 1863 – John Newlands put the elements in order of masses and noticed that each 8order of masses and noticed that each 8thth element shared similar properties. He called element shared similar properties. He called this the law of octavesthis the law of octaves

1869 – Dmitri Mendeleev used mass number 1869 – Dmitri Mendeleev used mass number and properties to order the elements and properties to order the elements

Newland’s Octaves

Newland discovered that

when he ordered the elements,

every 8th element seemed to have

similar propertiesHowever, the atoms

were ordered by atomic mass which led to some being ordered incorrectly

Mendeleev over came this problem by leaving gaps, which were later filled by newly discovered elements

This order was confirmed with the discovery of protons in the early 20th century

Eugene GoldsteinEugene Goldstein

1897 – the discovery of the proton1897 – the discovery of the proton

Alkali Metals

Alkaline Earth Metals

Transition Metals

Halogens Noble Gases

Colour and label your periodic table according to page 213 AQA chemistry book

As you go DOWN the group

They get MORE REACTIVE (larger atoms loose electrons more easily).The shells provide SHEILDING from the positive pull of the

nucleus so the outer electron is lost more easily

Have LOWER MELTING/BOILING points

Alkali Metals

Li

FrCsRbK

Na

Reactions with water React to form HYDROGEN and a

HYDROXIDE (alkali)1st 3 Float due to LOW DENSITY

React with non-metals to form IONIC COMPOUNDS.

White solids which dissolve in water

Form +1 ions by LOSING one electron

State SymbolsState Symbols

These symbols are used in some equations:These symbols are used in some equations:

(aq) aqueous solution(aq) aqueous solution

(l) Liquid(l) Liquid

(s) Solid(s) Solid

(g) Gas(g) Gas

e.g. e.g. 2K(s) + 2H2K(s) + 2H22O (l) O (l) → 2KOH(aq) + H→ 2KOH(aq) + H22(g)(g)

What is the general equation for alkali metals and water?What is the general equation for alkali metals and water?

Transition Metals

Ti Mn

CrYSc

Once the forth energy shell has 2 electrons, the 3rd energy shell can hold up to 18

electrons. This gives the transition metals similar properties and some special

properties e.g. magnetism

Many transition elements have ions with different charges e.g. Fe2+,

Fe3+

NiCoFe ZnCu

Higher melting/boiling points

Stronger and Harder

Much less

reactive

Useful as

Catalyst