GCSE - Chemistry - C1 Atomic Structure

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Chemistry Revision

C1 - Atomic Structure

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Formula, Elements, Compounds and Mixtures

  • ELEMENT - made up of a single type of atom 
  • COMPOUND - made up of 2 or more types of atoms and are chemically bonded and can't be separated 
  • MIXTURE - made up of 2 or more types of atoms and aren't chemically bonded so can be         separated

Naming Compounds

  • RULE 1 - When 2 elements jhoin together, they end in -ide
  • RULE 2 - When 3 or more elements join together and one is oxygen, they end in -ate
  • RULE 3 - When 2 of the same elements join together, the ending doesn't change (diatomic)
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Chemical Equations and Balancing

A chemical reaction is the process of breaking bonds in the reactants and making new bonds to form new substances. The reaction is irreversable.

Conservation of Mass

Atoms and therefore mass cannot be created or destroyed. The reactants have the same total mass as the products.

State Symbols                                 Balancing Equations

  • s- solid                                        Mg + HCl → MgCl2 + H2    
  • t - liquid                                       Mg + 2HCl → MgCl+ H2
  • g - gas 
  • aq - aqueous
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Separating Mixtures

Chromatography - separating pigments in inks. Each pigment travels a different distance up the filter paper 

Filtration - separating soluble substances from insoluble substances using filter paper and a funnel

Crystillisation/Evapouration - Separating salt from water by evapourating the water, leaving salt crystals

Distilation - separating a solute and solvent and collecting both separately

Fractional Distillation - separating 2 or more liquids, such as oils

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The Atom


  • The RELATIVE ATOMIC MASS is the number of protons and neutrons added together
  • The ATOMIC NUMBER is the number of protons
  • The number of protons is equal to the number of electrons because an atom has no charge
  • Protons and neutrons have a mass of 1. Electrons have nearly no mass.
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Electron configuration

  • The number of electrons is equal the amount  of protons (meaning the sme as the atomic number)
  • There can be a maximum of 2 electrons on the first shell and a maximum of 8 on all other shells
  • The amount of electrons on the outer shell is the group number of the element on the Periodic table.
  • The amount of shells an element has is the row that the element is found on in the Periodic table

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Isotopes and Ions

Isotope - an atom that has a different mass because of a different amount of neutrons in the           nucleus. The number of protons and electrons doesn't change.

Reletive Abundance of Isotopes

((Mass of 1st isotope x % of 1st isotope) + (Mass of 2nd isotope x % of 2nd isotope))/100

Ion - an atom that has gained or lost electrons to have a full outer shell. Must be drawn in               brackets and have the charge shown. Dots and crosses to show the change in electrons


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The History of the Atom

  • In the 1800's Dalton concluded that all matter is made of atoms and that atoms cannot be created, destroyed or broken down any further.
  • Thomson used the "Plum Pudding Model" to prove that atoms could be divided further into electrons. The electrons were inside positively charged matter.
  • Rutherford added a nucleus to Thomson's model that contained the positively charged matter and that the electrons orbited the nucleus.
  • Bohr furthered on Rutherford's model and come up with the theory of shells. The electrons orbiting the nucleus where on shells. 2 were on the first shell and 8 on every other shell after
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The History of the Periodic Table

  • Döbereiner put forward the "Law of Triads". It stated that the relative atomic mass of the middle element in the triad was similar to the average relative atomic mass of the other 2 elements. He only successfully classified 3 triads so his law wasn't accepted.
  • Newlands put forward the "Law of Octaves" meaning every 8th elemnt along his Periodic Table would have similar properties. He ordered elements by relative atomic but his theory wasn't accepted as iron was but with oxygen and sulfur.
  • Mendeleev put forward the "Periodic Law" that put elements with similar properties in a column together. The elements were ordered by relative atomib mass. There were gaps in Mendeleev's table but they were left in to represent elements that hadn't been discovered at the time. When new elements were discoverd they fit into Mendeleev's Periodic table just as he had predicted.
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Group 1 and Group 7

Group - Alkali Metals

  • The further down group 1 you go, the more reactive the elements get. The atom is larger and the 1 electron to lose to gain a full outer shell is further away from the nucleus and more shells are shielding the attraction.

Group 7 - Halogens

  • The furhter up group 7 you go, the more reactive the elements get. The atom is smaller and the 1 electron to gain to gain a full outer shell is closer to the nucleus and less shells are shielding the attraction.
  • Have very low melting and boiling points, are very poor conductors of heat and electricity, are diatomic and are toxins so have to be handled with care.
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Transition Metals


  • Shiny
  • High boiling and melting point - strong metallic bonds
  • Malleable
  • High density - shorter bonds
  • Conducts heat and electricity - free mocing electrons
  • Strong/hard
  • Ductile

Image result for metallic bond (http://www.bbc.co.uk/staticarchive/fba2965c626a450042effd6174b49257d3b3a69f.gif)

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