In your element

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  • Created by: Belinda
  • Created on: 30-05-11 12:34

The Atom & atomic number and mass number & isotope

Hydrogen does not contain neutrons.

Proton- relative mass= 1, relative charge= +1
Nuetron- relative mass=1, Relative charge= 0
Electron- Relative mass = 0, Relative charge= -1

Atom has the same number of protons as electons

The bottom number is atomic number = the number of protons
Top number is mass number = Total number of protons and neutrons

Isotopes = atoms of the same element with different numbers of neutron

They have the same chemical properties, same atomic number bu different mass number

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Relative atomic mass & electron configuration & re

Relative atomic mass = average for different isotopes of an element

Electron configuration = how electrons are arranged around the nucleus of an atomin shells

Element reaction depends on:
number of electrons in outer shell & the distance the outer most shell is from the influence of the nucleus.

Generally:

more electrons in the outer most shell = further they are from the nucleus & less reactive the element
Fewer electrons in the outer most shell equal = further away from the nucleus and more reactive the element is

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Reactivity of elements in groups & ionic binding &

Elements in group 1 all have 1 electron in their outer most shell

Elements in group 7 all have 7 electrons in their outer most shell

Elements in group 8 all have full outer shells

Sometimes electrons are completely transferred resulting in the formation of an ionic bond.

An ionic bond occurs between a metal and non metal atom.

 Each ion has a complete outer most shell.

Ionic compounds are neutral because the charges on the ions cancel eachother out.

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Ionic structures & electrolysis

Properties of Ionic compounds:
Giant lattice held together by the forces of attraction between the positive ions and negative ions

Ionic compounds:
- High melting and boiling points
- Strong electrostatic forces to hold them together
- Conduct electricity; when molten or in solution, charged ions to move about
- Often dissolved in water
- Crystalline due to regular arrangement of their ions

Electrolysis= Positively charged ions move to negative cathode & negatively charged ions move to positive anode

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Electrolysis of molten aluminium oxide & Pure meta

Molten aluminium oxide can be electrolysised to produce aluminium

aluminium oxide > aluminium + oxygen

Pure metal contains only atoms of that element. They are extracted from the ground and need to be purified.

Properties:
- Good conductivity (heat and electricty)
- Dense (heavy)
- Malleable (shape can be changed without damage)
- Soft (compared to alloys)
- Magnetic
- Shiny when polished
- High melting and boiling points
- Strong under tension and compression
- Sonorous (will ring when hit)
- Ductile (can be drawn into wire)

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Alloys

Metals are more useful when they are NOT pure = alloys

An alloy can have:
- Lower melting or boiling point
- Increased corrosion resistance
- Increased chemical resistance
- Increased strength and hardness

Examples:
- Pure iron isnt good for building = soft, stretches and corrodes
- Iron + Nickel + Chromium = Stainless steel

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Glossary

Alloys- a metal made by mixing a metal with another metal or substance; the alloy has different properties from the pure metal

Malleabilty- the ability of a metal to be hammered into different shapes without cracking or breaking

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