C1 Unit 1 Chemistry: Fundamental ideas

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C1 1.1: Atoms, elements and compounds

  • Substances that are made up of only type of atom are called element.
  • Elements in the periodioc table are arranged in columns which are called groups, groups contain elements with similar chemical proporties.
  • Compunds conatain more trhan one type of atom chemically bonded together.
  • An atom has a tiny nucleus in its centre which is surrounded by electrons.
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C1 1.2: Atomic structure

  • The nucleus of an atom contains protons and neutrons and electrons orbit the nucleus.
  • The number of electrons and protons in any atom is equal.
  • Neutrons have no charge so the nucleus overall has a positive since the charge on a proton is +1.
  • The charge on an electron is -1.
  • Overall an atom is neutral since the charges of the electrons and the protons cancel out.
  • The number of protons in each atom is called the atomic number.
  • The mass number is the number of protons plus the number of neutrons.
  • Number of neutrons=mass number - atomic number.
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C1 1.3: The arrangment of electrons in atoms

  • The chemical proporties of elements depend on how many electrons they have.
  • How reactive the an element is depends on how many electrons it contains in its outer shell.
  • Elements in group 0 are called noble gases because they are unreactive and have a full outer shell.
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C1 1.4: Forming bonds

Some atoms react by transferring electrons to form bonds, this happens when metals react with non-metals .

If the atoms that are reacting are both non-metal they share electrons to form chemical bonds.

When metals and non-metals react metals form positiviely charged ions and the non-metal forms negatively charged atoms.

Ionic bonds are the strong forces of attraction between positively and negatively charged ions.

Non-metals share electrons and react to form covalent bonds.

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C1 1.5: Chemical equations

  • No atoms are destroyed or created in a chemical reaction so the the total mass before the reaction is the same as the total mass after the reactions.
  • There is the same number of each type of atom on each side of a balanced symbol equation.
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