# Atomic Structure

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• Created by: Charlotte
• Created on: 08-04-13 21:56

## Atoms

Atoms

Elements are made of only one atomAll atoms have a nucleus this contains protons and neutrons which is surrounded by a Shell of electrons

ALL ATOMS OF THE SAME ELEMENT HAVE THE SAME NUMBER OF PROTONS!

·       Protons have a mass of 1 and a charge of 1+

·       Neutrons have a mass of 1 and no charge

·       Electrons have a negligible mass and a charge of 1-

Atoms are neutral because they contain the same number of protons and electrons.

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## Bonding/ Periodic Table

Bonding - Atoms can join together by:

·       Sharing electrons this is called covalent bonding

·       Transferring electrons this is called ionic bonding

Periodic Table

·       There are about 100 different types of elements

·       These elements are often displayed in the periodic table

·       Horizontal rows are called periods

·       Vertical columns are called groups

ARRANGED IN ORDER OF INCREASING ATOMIC NUMBER.

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## Mass Number / Atomic Number

Mass Number / Atomic Number

Mass Number / Atomic Number

·       2 Numbers written next to the symbol - called the mass number & atomic number

·       Mass number tell us the number of protons added to the number of neutrons in the nucleus of one atom.

·       Atomic number also known as the proton number, which tells us the proton number so, this tells us the number of protons in the nucleus. Neutral atom also tells us the number of electrons.

Example:

Sodium has a mass number of 23 and an atomic number of 11, this means:

·       11 protons (atomic number which is the bottom one normally)

·       11 electrons (atomic number which is the bottom one normally)

·       12 neutrons (mass number - atomic number)

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## Electronic Structure

Electrons

Electrons fill up the shell closest to the nucleus this is called the first shell. When this is full they then move to the second shell.

There is room for up to two electrons in the first shell and the second on is up to 8.

Example

Lithium atom has 3 electrons

·       2 in the 1st shell

·       1 in the second

·       Electronic structure of 2,1

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## Isotopes

Isotopes

Isotopes are different forms of the same element. This means that they have the same number of protons but a different number of neutrons.

Isotopes are: atoms of the same element, which have the same number of PROTONS but DIFFERENT number of NEUTRONS.

1. if they had different numbers of protons, they'd be different elements

2. Carbon - 12 and carbon - 14 are two isotopes of carbon.

Carbon - 12              carbon-14

6 protons               6 protons

6 electrons            6 electrons

6 neutrons            8 Neutrons

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