Atomic Structure

Atoms are some of the simplest particles to make up solids, liquids or gases. The atoms are always moving and may be joined together by special bonds

The Atom Atoms are made of three different things: protons, neutrons and electrons. The protons and neutrons are held together in the centre of the atom to form an object called the nucleus. The electrons can be found circling the nucleus at different distances from it. Chemical reactions involve the atom's electrons - mainly because these are on the outside of the atom and are the first thing that another atom will meet when it reacts with it. Nuclear reactions involve the atom's nucleus and may release large amounts of energy

 

Now answer these questions ... (write all numbers)

1. How many different particles make up the atom ?
2. How many different particles are in the nucleus ?
3. What particles are found outside the nucleus ?
4. Are all the electrons always the same distance from the nucleus ?
5. What particle, beginning with P, is found in the nucleus ?
6. What particle, beginning with N, is found in the nucleus ?
7. What particles are mainly involved in chemical reactions ?
8. Nuclear reactions may release large amounts of what ?

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What makes Atoms Different to Each Other ?

Each type of atom has a different number of protons, neutrons and electrons. The number of protons and neutrons affect the mass of the atom - how heavy it is. The number of electrons has a strong influence on how reactive the atom is.

How Many Electrons ? The number of electrons in the very outside of the atom are the ones that take part in chemical reactions. The atoms can be arranged in a table so that all the ones with one electron in the outer layer (or shell) are in the first column. Ones with two electrons are in the second column ... and so on. This table of atoms is called the periodic table. When the atoms react many of them try to make sure they get eight electrons in the outermost layer. So an atom with one electron on the outside (eg. sodium) will react very easily with an atom with seven electrons (such as chlorine).

In this way, sodium will lose its 'odd' electron and chlorine will end up with eight electrons on the outside - so both atoms will be happy!

 

... and now these questions (write all numbers)

1. Do all atoms have the same number of electrons ?
2. The electrons are found in layers - what is another name for these layers ?
3. How many electrons do many atoms try to get in the outer shell ?
4. How many electrons does sodium have in the outer shell ?
5. How many electrons does chlorine have in its outer shell ?
6. What is the name of the table which arranges the atoms according to their electrons ?
7. How many electrons are in the outer shell of the atoms in column one ?
8. How many electrons are in the outer shell of the atoms in the second column ?

You scored out of 8 on that test