Chemistry-fundamental ideas

Chemistry-fundamental ideas

1. Atoms

   • All substances are made from these
   • Contains a nucleus
     • Protons
     • Neutrons
   • Electrons on shells around the nucleus

2. Elements

   • Contains one type of atom
   • Atoms for each element are represented by a different chemical symbol
   • Elements arranged in periodic table
   • Groups in the periodic table contain elements with similar properties

3. Subatomic Particles

   • Proton
     • +1
   • Neutron
     • 0
   • Electron
     • -1
   • Atoms of a particular element have an equal number of protons and electrons
     • Atoms have no overall charge
   • Atoms of a particular element have the same number of protons
   • Atoms of different elements have different numbers of protons
     • Atomic number
   • Electron configuration
     • How the electrons are arranged around the nucleus in energy levels or shells
   • Periodic table
     • Arranges elements based on electronic structure
     • Elements in same group have the same number of electrons on the outer shell
     • Elements in the same group have similar properties
     • Across each period a particular energy level is gradually filled with electrons

4. Alkali Metals

   • Similar properties - same number of electrons on outer shell
   • React with non-metals to form ionic compounds
     • Metal ions have a single positive charge
   • React vigorously when added to water
     • Produce alkaline solution and hydrogen gas

5. Halogens

   • Same number of electrons in the outer shell (seven)
   • React with alkali metals to form ionic compounds
     • Halide ions have a single negative charge

6. Noble Gases

   • Unreactive gases
   • Stable electron arrangement

7. Mixtures and Compounds

   • Mixture consists of two or more elements/compounds that are not chemically combined
   • Compounds are substances in which the atoms of two or more elements are chemically combined
     • Held together by chemical bonds
       • Form chemical bonds by sharing electrons (covalent) or gaining/losing electrons (ionic)
   • When atoms form chemical bonds the arrangement of the outermost shell of electrons changes
     • Each atom gets a complete outer shell of electrons

8. Chemical formulae

   • Compounds are represented by a combination of numbers and chemical symbols called a formula
   • Chemists use formulas to show..
     • Different elements in a compound
     • Ratio of atoms of each element in the compound
   • H2O means (2 x H) + (1 x O)

9. Chemical reactions

   • Word equation showing substances that react on one side and substances formed on the other
   • Total mass of products in reaction are equal to total mass of reactants
     • No atoms are lost or made!!
   • Chemical symbol equations must always be balanced
     • Same number of atoms of each element on either side of the equation