Structure and bonding

Title• Atomic structure

Aim• to draw and label the sub atomic particles

of an atom.

This dotted line is called The Staircase – it divides metals (left) from non-metals (right)

A column is called a Group. There are 8

1 2 3 4 5 6 7 8

A row is called a PERIODVIDEO

Quick quiz

1. What is found in the periodic table?2. What are the rows called?3. What are the columns called?

4. What element is found in:a) Group 8 period 2- Ne (neon)b) Group 6 period 2- O (oxygen)c) Group 1 period 4- Na (sodium)

This dotted line is called The Staircase – it divides metals (left) from non-metals (right)

AtomsELEMENTS are made up of ATOMs.

ATOMs are all made up of protons, neutrons

and electrons.

The Nucleus – this

contains neutrons

and protons

Electrons – these orbit around the nucleus

Different elements have different types of atoms.

What the difference?

Protons =2 Protons =4

HeliumBeryllium

Atomic Number

• The atoms of same elements alwaysalways

contains the same number of protons. E.g.– Hydrogen atoms always contain 1 proton– Carbon atoms always contain 6 protons– Magnesium atoms always contain 12 protons

• The number of protons is the atomic number.

• It is the smaller of two number

12

C6

There are 3 parts of an atom Type of sub atomic

particleRelative charge

Proton +1 (positive)

Neutron 0 (neutral)

Electron -1 (negative)

1/2000 of the size of a proton

How Many Protons?

• Here is some data about elements taken from the Periodic Table.

• What is the atomic number of the elements?

23

Na11

56

Fe26

119

Sn50

19

F9

27

Al13

11 26 50 9 13

Activity

What element is it?

• Atomic number.

• 12-Magnesium (Mg)

• 8- Oxygen (O)

• 6- Carbon (C)

• 20-Calcium (Ca)

• 3- Lithium (Li)

• 2- Helium (He)

Atomic number

• Atomic number = number of protons.

• Atomic mass is the number of protons and neutrons added together

12

C6

Atoms

• In atoms

number of protons = number of electrons

So if the atomic number is 8 it will have,

8 protons

and

8 electrons

Why do atoms have NO

charge?

• Complete as a class

Atom Protons +

Electrons

-

Charge

Helium

Nitrogen

Oxygen

Magnesium

Sodium

Activity

Symbol

What is an isotope?

• Different forms of the same element.

• Same atomic number BUT a different number of neutrons and thus a different mass number.

•Eg O16

8

•99.76% of oxygen atoms have this configuration.

•0.04% have the mass number of 17

•0.20% have the mass number of 18

*Drawing Atoms*

Aim:• To accurate diagrams of the electron

structure of the first 20 elements.

How Are Electrons Arranged?• Electrons are not evenly spread.• The exist in layers known as shells.• The arrangement of electrons in these shells is often

called the electron configuration.electron configuration.

2nd Shell

1st Shell

3rd Shell

4th Shell

Electron configuration

• Shows how electrons are organised at an atomic level.

Shell 1st 2nd 3rd 4th

Max numbers of electrons

2 8 8 2

Which Shells Do Electrons go into?

• Opposites attract.• Protons are positive (+) and electrons are

negative (–) charged.• Electrons will occupy the shells nearest the

nucleus unless these shells are already full.

1st Shell: Fills this first

2nd Shell: Fill this next

3rd Shell: And so on

The Electrons in Carbon

The Electrons in Silicon

The Electrons in Neon

1+ ion ProtonsElectrons

1- ion ProtonsElectrons

Ions and Electron Structures

1. Ions are atoms that have either extra electrons added or electrons removed. e.g.

Atoms ProtonsElectrons

Lose 1 electron Gain 1 electron

So in ions the number of

electrons no longer equals the

number

of protons

Na Bye!

The Electrons in a Sodium IonIn the sodium atomatomAtomic number = number of protons = 11 Number of electrons = 11

Electron arrangement: 2.8.1 (Incomplete Shell)

Na+

Electron lost

Electron arrangement: 2.8 (Full Shells)

23

Na11

Mg

The Electrons in a Magnesium IonIn the magnesium atomatomAtomic number = number of protons = 12 Number of electrons = 12

Electron arrangement = 2.8.2 (Incomplete shell)

Mg2+

Electron arrangement 2.8 (Full Shells)

Bye!

Bye!

2 electrons lost

24

Mg12

The Lithium Ion

Li

3

2

1

1st Shell = 2: full

2nd Shell = 1: not full

2.1

1

•How many electrons?

•How many electrons in the first shell?

•How many electrons in the second shell?

What electron arrangement?

How many electrons to lose?

New electron arrangement? Include a diagram

2.(0)

Bye!Li+

7

Li3

Activity

The Boron Ion

B

5

2

3

1st Shell = 2: full

2nd Shell = 3: not full

2.3

3

•How many electrons?

•How many electrons in the first shell?

•How many electrons in the second shell?

What electron arrangement?

How many electrons to lose?

New electron arrangement? 2.(0)

Bye!

Bye!

Bye!

B3+

11

B5

Activity

Open to valence table 5.1

• Draw a before and after using a Bohr diagram showing the following atoms becoming ions.

• Sodium• Oxygen• Chlorine • Calcium • Nitrogen• Aluminium

Ionic Compounds• Once an ion has been created it will

attract ions of the opposite charge they form ionic compounds.

• For example magnesium + oxide = magnesium oxide

• To write this as a chemical formula you need to take into account the ions charges (valencies)

Magnesium has a positive charge of 2 while oxide has a negative charge of 2.

Ionic FormulasStep 1 - write the name and symbols (the positive goes first)Magnesium Oxide2+ 2-Mg OWrite the valencies above the symbols

Step 2 - crisscross the valencies to get correct subscripts and leave out the + & - signs

Magnesium Oxide2+ 2-

Mg2 O2

Step 3 - write the correct formula with subscripts

Mg2O2 = MgO

(you can simplify this to MgO as each has 2 they cancel each other out)

Ionic formulas• What happens when you try the following• Potassium + oxide

• Your new formula looks like this• potassium oxide• 1+ 2-• K2 O1

• K2O

• When the charge is one only you can leave this out

Ionic Formulas• Try these in your book (write ALL STEPS)

1. Calcium + oxide

2. Barium + oxide

3. Silver + chloride

4. Sodium + bromide

5. Lead + permanganate

Ionic formulas• When they get more complex-

• Zinc + nitrate• 2+ 1-• Zn (NO3)

• Zn(NO3)2

• Potassium + sulfate• 1+ 2-• K (SO4)• K2SO4

Creating an ionic compound

• Aim: to make the ionic compound Magnesium oxide and explain its bonding.

• What you know about Magnesium and Oxygen. Colour, solid liquid or gas, electron structure. Use pictures

Equipment & Safety

Equipment• Goggles• 2cm strip of Mg• Heat proof mat• Tongs• Bunsen burner

Safety• While heating Mg DO

NOT look directly at it.• Ensure all heated

material stays on heat proof mat

• Ties in

Observations

1. What did you see hear and smell?

2. What was the product formed?

3. What did it look like?

Explaining observations1. Why did you see or hear

something?2. How can you explain why

magnesium and oxygen have combined?

3. Use the electron configuration. 4. How many atoms form the

compound?5. Does the properties change of

Mg and O?6. Why does this happen?7. Write and equation to show

this chemical reaction.

• These are ions formed by the atom gaininggaining one or more electrons.

• They are called anionsanions. This is because during electrolysis they move towards the anode.

• The charge on the ions is equal to the number of equal to the number of electrons that the atom has gainedelectrons that the atom has gained.

• In equations the charge is usually shown above and to the right of the symbol. (E.g.. O2- ).

Negative Ions.

Gain 1 e- -

Gain 2 e- 2-

Gain 3 e- 3-

It is nearly always

non-metal atoms that

gain electrons

Ions usually have

OUTER electron

shells that are either completely full or else

empty

The Electrons in a Sulphide Ion.In the sulphur atomatomAtomic number = number of protons = 16 Number of electrons = 16

Electron arrangement: 2.8.6 (incomplete shell)

Electron arrangement 2.8.8 (Full shells)

2 electrons gained

S S2-

32

S16

The Electrons in a Fluoride Ion.

In the fluorine atomatomAtomic number = number of protons = 9 Number of electrons = 9

Electron arrangement: 2.8.7 (incomplete shell)

Electron arrangement 2.8.8 (Full shells)

1 electron gained

F F2-

19

F9

The Oxide Ion16

O8

O

8

2

6

1st Shell = 2: full

2nd Shell = 6: not full

2.6

2

•How many electrons?

•How many electrons in the first shell?

•How many electrons in the second shell?

What electron arrangement?

How many electrons to gain?

New electron arrangement? 2.8

O2-

Activity

Drag the words at the top to their correct places in the sentences.

Word check

1. Which of the following is not a sub-atomic particle?

A. Proton.

B. Isotope.

C. Neutron.

D. Electron.

2. The element Cobalt has a relative atomic mass of 59 and an atomic number of 27. Which of these is a true statement about each neutral cobalt atom?

A. It contains 59 neutrons.

B. It contains 27 electrons.

C. It contains 32 protons.

D. It contains equal numbers of neutrons and electrons.

3. The Periodic Table displays iron as shown below. This indicates that Fe atoms:

A. contain 56 neutrons.

B. contain 30 electrons.

C. contain 26 protons.

D. contains more protons than neutrons.

56

Fe26

4. Bromine consists of a mixture of two isotopes: Bromine-79 and Bromine-81

• Which of the following is true:

A. Both isotopes contain 35 protons.

B. Bromine 79 contains 46 neutrons.

C. Bromine 81 contains 44 neutrons.

D. Bromine-81 is more reactive than bromine-79.

80Br35