Structure and Bonding

Structure and Bonding

1. Electronic configuration of atoms

   • This is an lithium atom
     • A Lithium atom has 3 protons and 3 neutrons inside the nucleus with 3 electrons orbiting around the nucleus as shown.
   • 2,2,18 is the amount of electrons there can be on the outer shells. Not all atoms have 4 outer shells.
     • Noble gases have full outer shells which makes them unreactive

2. Protons + Neutrons = Atomic Mass/Weight

3. Atomic number can also be called the proton number as it the amount of protons in a atom

   • The amount of Protons in a atom = amount of Electrons, to balance the atom so that it doesn't have an overall charge

4. Subatomic particle

   • PROTON
     • NEUTRON
       • ELECTRON
   • Symbol
     • Relative mass
       • Relative charge
         • +1
           • No charge
             • -1
       • 1
         • 1
           • 0.00054
     • p
       • n
         • e

5. Molecule

   • Two ore more atoms joined by covalent bonds

6. Compound

   • Two or more elements chemically bonded together
   • Bonds form between atoms
   • Eg Iron Sulphide

7. Element

   • A substance that cant be broken down into anything simpler using reactions
   • Eg Iron

8. Mixture

   • A mixture is made from different substances that are not chemically joined.
   • Can be seperated easily
   • Eg Iron and Sulphur

9. Isotopes

   • Isotopes are the atoms of an element with different numbers of neutrons. They have the same proton number, but different mass numbers.
     • The Relative Atomic Mass for isotopes is calculated by taking an average of the different atoms
   • The nuclei of some isotopes are unstable. They can split up or ‘decay’ and release radiation. Such isotopes are called radioactive isotopes or radioisotopes.
     • Uses For Isotopes
       • Can be used to kill cancer cells
         • Smoke detectors
           • Sterilising medical equipment
   • Same atomic number
     • Same number of protons
       • Different mass numbers
         • Different number of neutrons
           • Same chemical properties
             • Isotopes have:

10. Covalent Bonding

    • Non metal atoms combine together by sharing electrons.
      • The shared pair of electrons holds the two atoms together
        • The group of atoms bonded together in this way is called a molecule.
          • The covalent bonds binding the atoms together are very strong
            • But there are only very weak forces holding the molecules to each other (the intermolecular forces).
              • Therefore, only a low temperature is needed to separate the molecules when they're melted or boiled.
        • a covelant bond = 1 or more pair of shared electrons
    • H20 dot and cross diagram
    • Covalent compounds are usually gases or liquids with low melting points or boiling points and they don't conduct electricity.
      • Examples: Carbon dioxide is a gas with a boiling point of -44°C. It doesn't conduct electricity. Water is a liquid with a melting point of 0°C. It doesn't conduct electricity.

11. Ionic Bonding

    • Atoms turn into ions when they lose or gain electrons.
    • Ionic bonding occurs between positive and negative ions, which attract each other and bind together to form ionic compounds. For example, sodium chloride consists of Na+ ions and Cl- ions bound together.
    • The formation of ionic compounds is often shown with dot and cross models.
      • if an atom loses one or more electrons, it becomes a positively charged ion
        • if an atom gains one or more electrons, it becomes a negatively charged ion
          • atoms gain or lose just the right number of electrons to produce an ion with a complete outer shell of electrons. This is sometimes called a stable octet.
    • A sodium atom and ion

12. Brownian Motion

    • Is the seemingly random motion of particles suspended in a liquid or gas resulting from their collision with quick atoms or molecules in the gas or liquid
      • Think it of it as the grain/pollen/rock etc as a football and the gas/liquid as a players. It looks as if the players are invisible and kicking round the ball which is visible.

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