In your books write the number of protons, neutrons and electrons found in each atom of these four elements. Mass Number = number of protons plus neutrons Atomic Number = number of protons

C 6 12

The electrons that surround the nucleus of an atom are arranged in shells. Each shell has a maximum number of electrons that can exist in that shell.

Up to 2 electrons can exist in the first shell Up to 8 electrons can exist in the second and third shell Up to 18 electrons can exist in the fourth and fifth shell 1 st shell holds a maximum of 2 electrons 2 nd shell holds a maximum of 8 electrons 3 rd shell holds a maximum of 8 electrons

H 1 1 H HYDROGEN: How many electrons does hydrogen have?

He 2 4 HELIUM: How many electrons does lithium have?

Li 3 7 LITHIUM: How many electrons does lithium have?

O 8 16 O Oxygen: How many electrons does oxygen have?

Ne Ne NEON: How many electrons does neon have?

Na Na What element is Na, how many electrons does it have?

Cl Cl What element is Cl, how many electrons does it have?

Ca Ca What element is Ca, how many electrons does it have?

Task  Draw the electronic structure of the first 20 elements

Task  Complete the table Element Electrons in 1st shell Electrons in 2nd shell Electrons in 3rd shell Electrons in 4th shell Group in periodic table hydrogen10001 lithium21 sodium magnesium20 neon8 sulfur80 calcium22 Q. What is the connection between the number of outer electrons and the group? © Mr Morton Science 2013

H OW REACTIVE ARE GROUP 1 METALS ? Metal How reactive is it? (1-3). 1 = The most reactive, 3 = least reactive Sodium Lithium Potassium

Elements in the same group have the same number of electrons in the outer shell. All group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shell These elements have __ electrons in their outer shells

As you move down through the periods an extra electron shell is added. Lithium has 3 electrons in the configuration 2,1 Potassium has 19 electrons in the configuration __,__,__,__ Sodium has 11 electrons in the configuration __,__,__ All of the elements in the same group have similar properties.

The number of electrons in the outermost shell is the same as it’s GROUP number. The number of shells is the same as it’s PERIOD number.

LithiumSodium Potassium Reactivity increases

1) Copy and complete the paragraph in your books using the words below. electrons, energy, group, nucleus, shells The electrons in an atom are arranged around the …………. in ………….. (energy levels). The electrons further away from the nucleus have more ………….. than those close to the nucleus. All elements in the same …………. of the periodic table have the same number of ……………. in their outermost shell. 2) Draw the arrangement of electrons in the following atoms and label each one with its electronic structure. a) Be b) B c) P d) Ar

3) Use the electron arrangements below to draw an atom, then use the periodic table on the back page of the textbooks to work out which element it is. A.2,7 B.2,8,2 C.2,8,6 D.2,4 E. 2,8,4 4) Why does the reactivity of the group one metals increase as you go down the group?

Starter  What can you remember about Atomic Structure? Grab a whiteboard and pen!

W HICH ELEMENT AM I?

I AM MADE UP OF 7 ELECTRONS.

A NSWER : N ITROGEN

I AM MADE UP OF 12 ELECTRONS

A NSWER : M AGNESIUM

I HAVE 2 ELECTRONS IN MY FIRST SHELL AND 3 ELECTRONS IN MY SECOND SHELL.

A NSWER : I AM B ORON

I HAVE 2 ELECTRONS IN MY FIRST SHELL, 8 IN MY SECOND SHELL AND 7 IN MY THIRD SHELL.

A NSWER : I AM C HLORINE

I HAVE TWO SHELLS. I N MY SECOND SHELL I HAVE 6 ELECTRONS.

I AM OXYGEN

I HAVE 3 SHELLS. I N MY OUTER SHELL I HAVE 3 ELECTRONS.

A NSWER : I AM A LUMINIUM

I AM A GROUP 7 ELEMENT IN THE SECOND PERIOD.

A NSWER : I AM F LUORINE

I HAVE THE ELECTRON CONFIGURATION OF 2, 8, 8,1

A NSWER : I AM POTASSIUM

I HAVE THE ELECTRON CONFIGURATION OF 2,8,7

I AM C HLORINE