© Boardworks Ltd 20071 of 44. 2 of 44© Boardworks Ltd 2007

© Boardworks Ltd 20071 of 44

2 of 44 © Boardworks Ltd 2007


What is the periodic table?

Mendeleev created the first modern periodic table. What does it show and why is it always in the same order?


What is an element?


Where were the elements made?

There are 92 naturally-occurring elements and about 15 artificially-produced elements.

Elements were originally made in stars. In the early stages of a star’s life, light elements, such as hydrogen and helium, are formed. These fused together to make heavier elements such as carbon.

Some of the even heavier elements were produced deep within stars and were sent out into the Universe when the stars exploded.

Most of the artificially-produced elements have only been made in nuclear reactors or particle accelerators.


What are elements made of?

Each element is made up of one type of atom, which is different to the atoms in any other element.

Gold is an element made up of only gold atoms.

Carbon is an element made up of only carbon atoms.

Oxygen is an element made up of only oxygen atoms.


What are atoms made of?


What is the atomic number?

Every element has a unique atomic number. This is the number of protons in the nucleus of each atom.

What is the atomic number of this helium atom?

A neutral atom must have equal numbers of protons and electrons, so the atomic number of an element also gives the number of electrons.

Helium has 2 protons, so its atomic number is 2.

Atoms are neutrally charged, so what links atomic number and the number of electrons?

electron

proton

neutron


What are the properties of elements?

A property is any characteristic feature of a substance.

Properties of sodium include:

The chemical properties of an element are determined by its atomic number.

Are there any patterns in the properties of the elements?

highly reactive

solid but melts easily

feels light (low density).

Can you name any properties of the element sodium?

A property is any characteristic feature of a substance.


Elements and atoms – true or false?



How was the periodic table developed?


How are the elements arranged?


The periodic table

Arranging all the elements by their atomic number and their properties led to the creation of…

…the periodic table

Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ?

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Na Mg Al Si P S Cl Ar

Li Be B C N O F Ne

H He


Missing elements!

In this periodic table the symbols are replaced by atomic numbers. Some of the numbers are missing – where?

87 88 89 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118

55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86

37 38 39 40 41 42 43 44 45 46 47 38 49 50 51 52 53 54

19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

11 12 13 14 15 16 17 18

3 4 5 6 7 8 9 10

1 2

Two more rows of elements fit here.

They are called the lanthanides and actinides.


The elements in the periodic table


Columns of elements

What are columns of elements called?

groups1 2 43 5 6 07


Rows of elements

periodsWhat are rows of elements called?

1

2

3

4

5

6

7


Complete the sentences – periodic table



Patterns: metals and non-metals

on the right (except hydrogen)

Where are these different types of elements grouped together in the periodic table?

metals

non-metals

between metals and non-metalssemi-metals

on the left and centre

Can you name a semi-metal element?

Semi-metals have some properties similar to metals and other properties similar to non-metals.


Patterns: physical state

Only two elements are liquids at room temperature.What are they?

liquids

Where are these elements of different states grouped together in the periodic table?

in the middle and on the right

solids

on the far right (except hydrogen)gases

on the left, in the centre and on the right

bromine and mercury


Metals to non-metals, solids to gases


Patterns: reactivity of metals

Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg

Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po

Rb Sr Y Zr NbMo Tc Ru Rh Pd Ag Cd In Sn

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga

Na Mg Al

Li Be

What happens to the reactivity of metals down a group?

Which is the most reactive metal?

increase in reactivity

incr

ease

in

rea

ctiv

ity

What happens to the reactivity of metals along a period?


Which metal is more reactive?


Patterns: reactivity of non-metals

increase in reactivity

Group 0 elements are the most unreactive of all elements.

For the remaining non-metals and semi-metals, reactivity increases up a group and along a period from left to right.

Which is the most reactive non-metal/semi-metal?

At Rn

Sb Te I Xe

Ge As Se Br Kr

Si P S Cl Ar

B C N O F Ne

He

incr

ease

in

rea

ctiv

ity

unreactive


Which non-metal is more reactive?



Patterns, atomic number and electrons

What links atomic number and the properties of elements?

The periodic table shows that patterns in the properties of elements are linked to atomic number.

atomic number = number of protons

atomic number = number of electrons

number of protons = number of electrons

Electrons!

As atomic number increases by one, the number of electrons also increases by one.

This means that the elements in the periodic table are also arranged in order of the number of electrons.


How are electrons arranged?

Electrons are arranged in shells around an atom’s nucleus. (The shells can also be called energy levels).

This electron arrangement is written as 2,8,8.

1st shell holdsa maximum of

2 electrons

2nd shell holdsa maximum of

8 electrons

3rd shell holdsa maximum of

8 electrons

Each shell has a maximum number of electrons that it can hold. Electrons will fill the shells nearest the nucleus first.


Electrons in period 1

Elements in period 1 only have electrons in the first shell.Why are there only two elements in period 1?

The first shell can only hold a maximum of two electrons,so period 1 only includes the elements hydrogen and helium.

What is special about the outer shell of helium?

1 2

H He

1 2 43 5 6 07

1



Elements in period 2 all have a complete first shell.

The second shell is completed one electron at a time going across the period from left to right.

What is special about the outer shell of neon?

2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8

Li Be B C N O F Ne

1 2 43 5 6 07

What happens to electrons in the second shell in period 2?

2



2,8,1 2,8,2 2,8,3 2,8,4 2,8,5 2,8,6 2,8,7 2,8,8

Elements in period 3 have complete first and second shells.

The third shell is completed one electron at a time going across the period from left to right.

What happens to electrons in the third shell in period 3?

Na Mg Al Si P S Cl Ar

1 2 43 5 6 07

What is special about the outer shell of argon?

3


What are the patterns of electron arrangement?

Consider the electron arrangements of the first 20 elements in the periodic table.

What is the pattern of outer shell electrons in a group?

2,8,1 2,8,2 2,8,3 2,8,4 2,8,5 2,8,6 2,8,7 2,8,8

1 2 43 5 6 07

1

2

3

4

2,1 2,2 2,3 2,4 2,5 2,6 2,7 2,8

1 2

2,8,8,1 2,8,8,2

What is the pattern of outer shell electrons across a period?

What is the pattern of full electron shells in a group?


Electron trends in the periodic table

Trends down a group:

The point at which a new period starts is the point at which electrons begin to fill a new shell.

The number of a group is the same as the number of electrons in the outer shell of elements in that group,except for group 0.

the number of outer shell electrons is the same;

the number of complete electron shells increases by one.

the number of outer shell electrons increases by one;

Trends across a period:

the number of complete electron shells stays the same.


Electrons and groups


Groups and periods


What’s the electron arrangement?


Names of groups in the periodic table


Periodic table and electron structure



Glossary

atomic number – The number of protons in an atom. Sometimes called the proton number.

electron arrangement – A shorthand way of writing the number of electrons in an atom’s electron shells.

element – A substance made up of only one type of atom.group – A column in the periodic table containing elements

with the same number of outer shell electrons and similar chemical properties.

period – A row in the periodic table containing elements with the same number of full electron shells.

periodic table – The table that lists all the elements in order of increasing atomic number, arranged into groups and periods.

property – Any characteristic of an element.


Anagrams


Multiple-choice quiz

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© Boardworks Ltd 20071 of 44. 2 of 44© Boardworks Ltd 2007