REVIEW OF THE ATOM term 4. ATOMIC STRUCTURE + electron orbit proton neutron.

REVIEW OF THE ATOM term 4

ATOMIC STRUCTURE

+

electronorbit

protonneutron

Definitions (refer to handout)

Atom – small particles that make up everything around us (matter).

Element – If a substance is made up of only one type of atom. Eg. Zinc, Oxygen, Copper.

Compound – a substance that contains two or more different elements that are chemically combined. Eg. Copper Sulphate, Water.

Mixture – a substance that contains two or more different substances that are not chemically combined.

Proton – a positive charged object held within the nucleus of an atom. Neutron – an uncharged object held within the nucleus of an atom.

Electron – a negatively charged object that is free to move around the nucleus.

Atomic Number – the number of protons in an atom. Mass Number – the number of protons and neutrons in

an atom. Atomic Number – the average Mass Number of all the

different isotopes of an element. Isotope – when two atoms have the same number of

protons but a different number of neutrons (therefore a different mass number).

Ion – an element or a compound, which takes on a charge due a variation between the number of protons and electrons, it possesses.

Ionic Charge – the charge of an atom. Eg. Oxygen contains 8 protons and 10 electrons, therefore 8 positive charges and 10 negative charges, i.e. 2- charge.

Definitions (refer to handout)

Question: Complete the following table

Element Symbol Atomic # Mass # Protons Neutrons

Hydrogen

2

12

Fe

79

Answers: Complete the following table

Element Symbol Atomic # Mass # Protons Neutrons

Hydrogen H 1 1 1 0

Helium He 2 4 2 2

Carbon C 6 12 6 6

Iron Fe 26 56 26 30

Gold Au 79 197 79 118

How do you find the Charge of an ion?

If it is a Group A Element - 1A = 1+, 2A = 2+, 3A = 3+, 4A = ??, 5A = 3-, 6A = 2-, 7A = 1-, 8A = 0. (See Periodic Table)

Question: Complete the following table

Symbol Atomic # Protons Electrons Charge

H 0

Na 11 10

F -1

20 18

Answers: Complete the following table

Symbol Atomic # Protons Electrons Charge

H 1 1 0 1+

Na 11 11 10 1+

F 9 9 10 -1

Ca 20 20 18 2+

Finding Chemical Formula’s

When ions bond together, they donate or receive electrons so that the new substance will have no net charge! To do this the number of positive charges is equal to the number of negative charges, therefore cancelling each other out.

Eg. Sodium + Chloride, Na+ + Cl- NaCl.

When balancing chemical formulas…

1. write the charge of each ion,

2. cross multiply,

3. simplify the ratio (if need be).

Eg. Magnesium sulphide

= Mg2+ + S2-

= Mg2S2 = Mg1S1 = MgS

Question: Find the formula for the following compounds

1. Lithium bromide

2. Calcium flouride

3. Potassium oxide

4. Hydrogen sulphide

1. Li+ + Br- LiBr

2. Ca2+ + F- CaF2

3. K+ + O2- K2O

4. H+ + S2- H2S

Ions

Ions - are atoms or groups of atoms that have a positive or negative charge. Ions are formed when an atom gains or loses and electron.

Cations - are ions, which have a positive charge (due to losing electrons)

Anions - are ions, which have a negative charge (due to gaining electrons)

Polyatomic ions - are groups of atoms that have a charge and act as a unit. Eg. SO4

2- contains 1 Sulphur and 4 Oxygen atoms and carries a 2- charge.

Diatomic elements - are two atoms of the same element bonded together. Eg. H2, I2, Br2, Cl2, O2, N2, Hg2,

Questions: Determine the charge of each of the elements listed and identify if they are anions or cations

1. Zinc2. Sulphur3. Sodium4. Potassium5. Neon6. Manganese (II)7. Magnesium8. Chlorine9. Aluminium10. Iron (III)

1. 2+, cation

2. 2-, anion

3. 1+, cation

4. 1+, cation

5. 0, neutral

6. 2+, cation

7. 2+, cation

8. 1-, anion

9. 3+, cation

10. 3+, cation

Questions

1. Fill in the table

Chlorate Sulphate Phosphate Sulfite

ClO3-

Hydrogen

Copper(II) Cu2+ Cu(ClO3)2

magnesium

Barium

Lesson Summary

Several Definitions (Atom, Element, Compound, Mixture, Proton, Neutron, Electron, Atomic Number, Mass Number, Atomic Number, Isotope, Ion, Ionic Charge, Cations, Anions, Polyatomic ions, Diatomic elements)

Writing chemical formulas

Lesson 1 Homework Questions

Name of Compound Ions Involved Formula

Lead(II) nitrate Pb2+, NO3- Pb (NO3)2

Zinc carbonate

Barium chloride

Potassium sulphate

Silver oxide

Sodium carbonate

Copper(II) nitrate