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C1 1.1 Atoms, Elements and Compounds
Friday 4th May 2012
Year 9
Garendon High School
Title: Atoms, Elements and Compounds
• Objectives: describe atom structure, the periodic table and elements and compounds.
• I must be able to describe the structure of an atom
• I should be able relate the numbers on the periodic table to atom structure
• I could define the terms ‘element’ and ‘compound’
How do you think we get such a variety of substances?
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Atoms Atoms are the “building blocks” of all matter and are the simplest form of molecule. They are all made up of protons, neutrons and electrons. They look something like this:
The nucleus – this contains neutrons and protons
electrons – these orbit around the nucleus
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The structure of the atom
ELECTRON – negative, mass nearly nothing
PROTON – 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
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Mass and atomic number
MASS NUMBER = number of protons + number of neutrons
SYMBOL
PROTON NUMBER = number of protons
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Mass and atomic number How many protons, neutrons and electrons?
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Electron structure Consider an atom of Potassium:
Potassium has 19 electrons. These are arranged in shells…
Nucleus
The inner shell has __ electrons
The next shell has __ electrons
The next shell has __ electrons
The next shell has the remaining __ electron
Electron structure
= 2,8,8,1
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Mendeleev
Periodic table
The periodic table arranges all the elements in groups according to their properties.
Horizontal rows are called PERIODS
Vertical columns are called GROUPS
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He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg
Fact 1: Elements in the same group have the same number of electrons in the outer shell (this
correspond to their group number)
E.g. all group 1 metals have __ electron in their outer shell
These elements have __ electrons in their outer shells
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He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg
Fact 2: Most of the elements are metals:
These elements are metals
This line divides metals from non-metals
These elements are non-metals
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H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Fe Ni Cu Zn Br Kr
Ag I Xe
Pt Au Hg
Fact 3: (Most important) All of the elements in the same group have similar PROPERTIES.
E.g. consider the group 1 metals. They all:
1) Are soft
2) Can be easily cut with a knife
3) React with water
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Elements If a solid, liquid or gas is made up of only one type of atom we say it is an element. For example, consider a tripod made up of iron:
These atoms are ALL iron – there’s nothing
else in here
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Compounds
Compounds are different to elements. They contain different atoms. Here is one example:
Methane
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1
Sodium chloride (salt)
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2
Mg Mg Mg Mg
Mg Mg Mg Mg
Mg Mg Mg Mg
Mg Mg Mg Mg
Magnesuim, Mg
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3
Glucose
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4
Water, H2O
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5
Hydrogen
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6
Oxygen, O2
O O
O O
O O
O O O
O
O O
Plenary
• Think , pair, share
• Write down 5 facts you’ve learnt individually
• Then discuss with your pair and add any facts you don’t have
• Discuss your facts with another pair and do the same
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