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How many different substances can you think of?

How many different substances?

There are millions of different substances! What are they allmade of?


All substances are made of tiny particles called atoms.

Many substances are made up of different types of atoms.

iron, aluminium, silicon, oxygen and boron atoms

carbon, nitrogen, hydrogen, oxygen and sulfur atoms

hydrogen and oxygen atoms carbon and hydrogen atoms

All substances are made of atoms


What atoms are you made of?

Atoms are the smallest part of an element. Different elements join together in different ways to make all the materials in the Universe, from rocks to air.

Just like all materials in the Universe, humans are also made of atoms.

Which atoms do you think are most common in the human body?

oxygen (65%)

other (%)sulfur (0.25%)potassium (0.35%)

phosphorus (1%)calcium (2%)nitrogen (3%)

carbon (18%)hydrogen (10%)


How big are atoms?

Atoms have a diameter of about 0.00000001 cm, which is far too small to be seen with your eyes.

In one glass of water there are around:

However, microscopes called Scanning Tunnelling Microscopes allow scientists to see the outlines of atoms.

12,000,000,000,000,000,000,000,000 oxygen atoms

24,000,000,000,000,000,000,000,000 hydrogen atoms.


Atomic zoom


Who discovered the atom?



An element is a substance that is made of only one type of atom. Elements are the simplest substances in the universe.

What is an element?

Copper is an element made up of copper atoms only.

Carbon is an element made up of carbon atoms only.

Helium is an element made up of helium atoms only.


What are molecules?

Molecules are made up of two or more atoms. Molecules can be formed by two atoms of the same element, or by atoms from two or more different elements.

Oxygen is an element made up of oxygen atoms only.

How many atoms are there in one oxygen molecule?

Other elements that form molecules include hydrogen, nitrogen, chlorine and bromine.


Element or compound?


Who discovered the elements?

Some elements, such as silver and gold, have been known about and used by people for centuries. However, many of the elements were only discovered in the 18th and 19th century.

For example, British scientist Joseph Priestley discovered oxygen when he experimented with heating gases.

At the start of the 20th century, Marie Curie and other scientists discovered radioactive elements like polonium and francium. Which countries were these elements named after?

Other scientists, such as Humphrey Davy, used electrolysis to isolate elements such as sodium and potassium for the first time.


How many elements are there?

There are currently 117 elements that have been discovered, 94 of which are naturally occurring. The remaining 23 elements only exist under laboratory conditions.

How many naturally-occurring elements can you name?


How are artificial elements made?

The first element to be artificially created was technetium, which was discovered in 1937 by Italian scientists working with the naturally-occurring element molybdenum.

Since then, other artificial elements have been made in particle accelerators. CERN is one of the world’s largest particle accelerators. It is situated underground on the French-Swiss border and is run by scientists from all over Europe.

Most artificial elements are very unstable and usually onlyexist for milliseconds before they decompose.


How does CERN work?



Symbols for elements

Each element can be represented by a symbol.

For many elements, the symbol is the start of the name, for example H = hydrogen or Li = lithium. Can you think of any other symbols like this?

However, some of the symbols are not always as you might expect; for example, Pb = lead. Can you think of any other elements with unexpected symbols?

The first letter of an element’s symbol is always a capital letter, e.g. N (not n) for nitrogen.

If there are two letters in the element’s symbol, the second letter is always a small letter, e.g. Co (not CO) for cobalt.


Chemical symbols game


Why are symbols important?

Why might scientists find it easier to use symbols for elements rather than names?

Elements have different names in different languages, e.g. in Portuguese, nitrogen is called ‘azote’, and iron is called ‘ferro’.

The current system for naming elements and compounds was devised by the International Union of Pure and Applied Chemistry (IUPAC) so that scientists all around the world could communicate without confusion.

Symbols are quicker to write than names, and can be easily used in chemical formulae, diagrams and equations.


Match the element


Spelling with symbols activity


Spelling with symbols

Write down the symbols for each element listed and use these to spell out a word that matches the clue.

1. Board game: carbon, helium, two sulfurs

2. Relative: sulfur, oxygen, nitrogen

3. Fuel: carbon, oxygen, aluminium

4. Group of fish: sulfur, hydrogen, oxygen, aluminium

5. For the rubbish: boron, iodine, nitrogen.

CHeSS

SON

BIN

How many words can you spell using symbols?

COA

SHOA


The atoms of some elements join together in molecules. Combining the symbols of the atoms in a molecule gives you the formula for the molecule.

What is the formula for the molecules in each element?

oxygen

hydrogen

nitrogen

O2==

H2==

N2==

Symbols for molecules of elements

This tells you that there are two atoms in each molecule.



The periodic table

All the known elements are shown in the periodic table.

Can you spot any patterns in how the elements are arranged in the periodic table?


Who invented the periodic table?


How are the elements arranged?

The elements in the periodic table are arranged in families called groups and periods. A group is a vertical column in the periodic table; a period is a horizontal row.

For example, all the elements in group 0 are very unreactive gases at room temperature, while all the elements in group 1 are very reactive metals.

The elements in groups tend to have similar properties.

groups 0 to 7p

erio

ds

1 to

6


Solids, liquids and gases

Why are some symbol names in the periodic table, below, shown in different colours? (clue: think about group properties)

Bromine and mercury are liquids at room temperature; all the other elements are solids or gases.


Metalloids

Metals are on the left and in the centre of the periodic table.

Non-metals are located mostly on the right.

Metalloids sometimes behave like metals and sometimes like non-metals.

Silicon and germanium are examples of metalloids.

Metalloids are located between metals and non-metals in the periodic table.


Metals, non-metals and metalloids



Glossary


Anagrams


Multiple-choice quiz

Science

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