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Is fire a physical or chemical change?
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Chemical reactions: reactant(s) product(s) oxygen + gasoline
Carbon dioxide + water vapour + energy (heat and light) oxygen + wood oxygen + hydrocarbon
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Chemistry Review Matter Pure substances Mixtures Compounds Elements
made of 2 or more pure substances Made of only one kind of particle Elements Compounds Made of only one kind of atom Made from 2 or more elements in a fixed ratio sodium chloride (NaCl) iron oxide (FeO) hydrogen peroxide (H2O2) Gold (Au) Sodium (Na) calcium (Ca)
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Chemistry Review Matter Pure substances Mixtures Solutions
made of 2 or more pure substances Made of only one kind of particle Mixtures Mechanical mixtures Two or more visible phases Solutions One visible phase solid – metal alloys (steel, karat gold) liquid – coffee with cream, milk and gaseous - air Concrete, marbles and sand, pizza! Phase: describes the appearance of a region of matter
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Atoms and Molecules Elements are composed of single atoms that are all the same Some special elements such as oxygen, hydrogen and nitrogen exist as molecules – O2, H2, N2 Molecules are particles that consist of 2 or more atoms bonded together Compounds are molecules of different sizes H2O, NaCl, which are small molecules C12H24O12, which is larger (table sugar, sucrose)
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And some are VERY large!
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Periodic Table of the Elements
Group or family period
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Atomic Structure Each element has unique physical and chemical properties This is based on the number of each kind of subatomic particle it is composed of: Positively charged particles in the nucleus Protons (1 amu) Negatively charged particles in a cloud around the nucleus Electrons (1/2000 amu) Neutral particles in the nucleus Neutrons (1 amu)
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Atomic structure The Periodic Table contains a lot of information about each element. Using the key included on each Periodic Table will help you find that information. 4 Atomic number Be Chemical symbol 9 Atomic mass
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Be 9 4 5 Beryllium Standard atomic notation: chemical symbol
number of protons first letter is always uppercase and the second letter is lowercase 9 Be number of electrons 4 atomic number mass number or atomic mass 5 Equals the mass of protons plus the mass of the neutrons chemical family metals number of neutrons
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Bohr-Rutherford diagram
2 8 8 Which element is this? phosphorus
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Bohr Rutherford diagrams
p n
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beryllium 4p 5n
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Name of molecule Number of atoms Cl2 chlorine 2 H2 hydrogen O2 oxygen
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sodium hydrogen carbon oxygen
Compound Compound Name Elements present # of atoms of each element H2O water hydrogen oxygen 2 1 CO2 carbon dioxide carbon oxygen NaHCO3 sodium bicarbonate sodium hydrogen carbon oxygen 3 NaCl sodium chloride sodium chlorine
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Compound Compound Name Elements present # of atoms of each element H2O2 hydrogen peroxide hydrogen oxygen 2 NaF sodium fluoride sodium fluorine 1 CaCl2 calcium chloride calcium chlorine Al2O3 aluminum oxide aluminum oxygen 3
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Chemical Change In a chemical change the reactants will become new products with new physical and chemical properties There are 4 indicators of a chemical change:
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Heat or light is given off…
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…a new colour appears …
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… a gas is produced…
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… a solid (a precipitate) forms in a liquid
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Physical Change State some properties of matter: State Colour Clarity
Crystal form Lustre Hardness Malleability etc
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Physical Change Physical changes do not result in a new substance being made Example – the three states of matter solid liquid gas heat heat No matter the state it’s still water! – it just goes through a change of state
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Physical Change Solubility – e.g. salt dissolves in water to make “salt water” – the salt particles spread apart in the water but they remain salt (nothing new is formed)
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Burning candle Chemical Change – wax is the fuel that produces heat and light, carbon dioxide and water vapour Physical change – wax melts when it gets hot and solidifies when it gets cold
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Physical (P) or Chemical (P) change Reason
Description Physical (P) or Chemical (P) change Reason Hardboiled egg C New colour, new texture, change in clarity Clear green liquid is mixed with a clear colourless liquid and a solid blue substance appears New colour precipitate forms Sugar in coffee P solubility Metal placed in acid and bubbles of gas appear bubbles of gas
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Hazardous Household Product Symbols
caution flammable warning explosive danger corrosive poisonous
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WHMIS International system
Needed because the materials used in the workplace are often much more dangerous than those used in homes Workplace Hazardous Materials Information System
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WHMIS Poisonous and infectious material causing immediate and serious toxic effects Oxidizing material Flammable and combustible material Compressed gas Dangerously reactive material Corrosive material Material causing other serious toxic effects Biohazardous and infectious material
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MSDS Material safety data sheet
Every hazardous product must be labeled and an MSDS sheet provided by the manufacturer Product label
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Material safety data sheet
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