reactions and equations

• A balanced equation shows the relative numbers of atoms on both sides.
• New substances are made in chemical reactions but not in physical changes. In both cases, the number of atoms does not change and so there is no overall change in mass. We represent

  chemical reactions using equations (containing words or symbols).
• 2H2(g) + O2(g) → 2H2O(l)　　　　　　　　　　　　　　　　　　　　　　　　　　　　　The little numbers show the number of atoms in molecules of hydrogen, oxygen and water.　　　　　　　　　　　　　　　　　　　　　　　The large numbers show the number of molecules.

  The letters in brackets are state symbols (g = gas, l = liquid, s = solid, aq = dissolved in water).
• Gas pressure is caused by the force of the particles hitting the walls of the container.
• (Change that increase gass pressure)

  Increase the tempreture=Particals move faster,so hit the wall with more force and more often.

  Increase the number of particals in container=Particals get close together and hit the wall more often.

  Decrease the volume of container=Particals get close together and hit the wall more often.
• Reactivity serise-list of metals in order to reacticity. most reactive one at top to least reactive one at bottom.
• Lithium（metals）＋water→Lithiumhydroxide＋Hydrogen gas
• Sodium(metals)＋Oxygen→Sodium oxide
• Most metals react with oxygen from the air to form metal oxides. This is an oxidation reaction.
• Atoms contain a nucleus made up by the protons and neutrons(center part)
• Electrons move around nucleus in atomic structure
• The number of protons is the atomic number or proton number.
• In periodic table,elements are arranged by atomic number
• Neutrons＋protons=mass number
• The vertical columns in the periodic table are

  groups and the rows are periods.
• Mass-proton and neutron

  Atomic number- is same as electrons

  Neutrons-Mass-protons

  
• Hydrocarbon＋oxygenn→carbondioxide＋water


  hydrocarbon is made up by hydrogen and carbon.Conbust in plentiful supply of air and form carbondioxide and water.
• The test for oxygen is that it relights a glowing splint.(test of oxygen=Is there oxygen?)
• Exothermic reaction-transfer enrgy from the reactants to surrounding
• Endthermic reaction -transfer enrgy from the surrounding to the reactants
• Explosive mixtures-fuel and oxidizer(爆発性混合物)
• Explosive mixture contain oxidising agent to catch more oxygen which helps substance to react faster.The rate is also increased by the increase of tempretute,concentration of a reactant and surface area.
• Thermal decomposition reactions, in which a compound is broken

  down by heat, require a constant supply of energy to keep them going.
• An input of energy from a flame or spark is needed to start the combustion reaction by breaking

  some bonds in the reactants.