gcse chemistry year 9

• What are the 3 types of bonding?

  Ionic, Metallic, Covalent
• Ionic bonding is between metals and non metals
• Metallic bonding is between metals and metals
• Covalent bonding is between non metals and non metals
• Where are the protons found?

  In the nucleus
• There can fit 2 electrons in the first energy level.
• There can fit 8 electrons in the second and third energy level.
• Group number tells you how many eletrons are in the outer shell of an atom.
• The outermost electrons are the ones involved in reactions.
• Noble gases have a full outer shell
• A full outer shell means a stable electronic configuration.
• He atoms have a full outer shell. This means they are not attracted to other He atoms. What state does this make them?

  Gas State
• An isotope of an element has the same number of protons and electrons but different numbers of neutrons.
• What are the three naturally existing isotopes of hydrogen?

  protium, deuterium, tritium
• An ion is a charged atom that has gained or lost electrons. It has a stable/full outer shell
• When ions have lost electrons, they are positively charged.
• When ions have gained electrons, they are negatively charged.
• What is the electronic configuration of Magnesium?

  2,8,2
• What is the electronic configuration of a Magnesium ion?

  2,8
• Is a Magnesium ion positive or negative?

  Positive
• Is a Chlorine ion positive or negative?

  Negative
• A covalent bond is where two or more non metals share outer electrons to obtain a stable outer shell.
• CO2 is the bond between two oxygens and one carbon.
• H2O is the bond between two hydrogens and one oxygen
• Metals are arranged in layers in a regular pattern.
• Electrons in the outer energy level of a metal delocalise. This makes a sea of delocalised electrons.
• Delocalised electrons are free to move through the structure. This allows them to carry charge making them good conductors of electricity and heat.
• In covalent bonds, one line between the elements (e.g. in H-O-H) means there is one shared pair between the two which it is touching. Two lines mean two shared pairs, and onwards.
• What is the relative charge of a neutron?

  0
• The relative charge of a proton is +1.
• The relative charge of an electron is a -1.
• What is the relative mass of a neutron and/or proton?

  1
• What is the relative mass of an electron?

  1/2000 or very small
• An atom has no charge because the number of protons and number of electrons are equal.
• Metals form positive ions.
• There is a strong force of attraction between negative and positive ions.
• Group 7 gases are known as the Halogens.
• As we go down group 7, the outer shell electrons are getting further away from the positive nucleus. The inner energy levels are filled with electrons. This means it is harder to attract in a negative electron into the shell. This is called electron shielding. This is why as you go down the group, the elements become less reactive.
• Group 1's reactivity increases as you go down the group. Group 1 need to lose 1 electron for a stable outer shell. This means as the atoms gets bigger with more energy levels, the outer electrons are further away from the nucleus so they are easier to lose (making the element more reactive).
• Why is K more reactive than Li?

  >Group 1 react by losing their 1 outer electron.

  >When you go down the group, the electrons get further away from the positive nucleus, meaning it is easier to lose - due to the decreased attraction and increased electron shielding.

  >K is lower down the group than Li, meaning it is easier for K to lose an electron than it is for Li.