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Chemistry - Science 10
REVIEW
Classification of MatterMATTER
MIXTURES PURE SUBSTANCES
SUSPENSIONSParticles of one of the substances remain partly clumped together Ex/Orange Juice
MECHANICAL Particles of the different substances remain clumped together. Ex/ cereal,nuts,bolts,pepper
SOLUTIONS Particles of thedifferent substancesare completely mixedtogether.Ex/ Coffee with sugar
ELEMENTS Contain only asingle type of atomEx/ Gold-Au or Calcium-Ca
COMPOUNDS Contain 2 or moretypes of atoms, joinedtogether.Ex/ Ethanol CH3CH2OH
Two Types of Mixtures
Heterogeneous- Different from place to place Not evenly mixed Included suspensions and mechanical mixtures Chocolate chip cookie, gravel, soil
Homogeneous- The same throughout Evenly mixed solutions Kool-aid, sea water, air
Pure Substance
Elements- Simplest kind of matter Can’t be broken down further All one kind of atom About 120 kinds of elements Each has a 1 or 2 letter symbol Each behaves differently Everything else is made up of them
Pure Substances
Compounds- Made of two or more elements chemically combined Atoms combine together to make molecules All molecules of a compound are the same
They mix in the same ratio Compounds behave completely differently
from the elements that make them Ex. Water H2O–liquid puts out fire: hydrogen
burns, oxygen supports combustion
Physical vs. Chemical Changes Physical Changes: No new substance has been
formed.(ex/ ice cube melting, or crumpling a piece of paper.
All the molecules stay the same Might look a little different Keeps original properties Changing phases Making a mixture Cutting Grinding Dissolving
Chemical Changes: If one or more substances have been produced, substances with properties different from the starting materials, then a chemical change has taken place.
Products are not at all like the reactants Makes new odor, color, etc. Completely new properties
Clues to tell you a “Chemical Change” has taken place:
A new colour may appear. Heat or light may be given off. Bubbles of gas may be formed. Solid material may form in a liquid. The change may be difficult to reverse.
Chemical Reactions
Chemical Reaction is another term for chemical change. (ex. Fast- fireworks, or slow- rust)
Starting materials are called reactants. (Found on the left of the arrow in a chemical equation)
Any substance produced in the reaction is a product. (on the right of the arrow).
Word Equations
Word equations tell us the names of the reactants and products in a reaction. Reactants on the left,(of the arrow) products on the right.
Note: It does not tell us the amounts of the atoms/elements required to make the reaction go!
Ex/ SodiumChlorine-----Sodium Chloride
Mass and Chemical Change
The Law of Conservation of Mass: In a chemical reaction, the total mass of
the reactants is always equal to the total mass of the products
Chemical Formulas
Tell the element and number of atoms in a molecule
Symbols identifies the element Subscripts tell the number of atoms Don’t write one as a subscript
Chemical Formulas
H2O
2 Hydrogen atoms 1 Oxygen atom
subscript
Chemical Formulas
C12H22O11
12 Carbon atoms
22 Hydrogen atoms
11 Oxygen atoms
Chemical Properties
Used to describe how substance reacts How it changes
By combining with other substances Or breaking apart
Reactivity how a substance combines with other substances
Things like flammability, rusting, etc.
Physical Properties
Can be observed or measured without changing the composition
Melting point , boiling point, hardness, odor, ability to conduct electricity and heat
Density – how heavy something is for its size Ratio of mass to volume If the density of substance is less than its
surroundings, it floats
Density
Found by dividing the mass by volume D = m
V Units of g/mL or g/cm3
Water has a density of 1 g/mL
Law of Conservation of Energy
In all chemical changes, energy cannot be created or destroyed
All the energy you put in, you get out It might be hard to count
KINETIC MOLECULAR THEORY
•All matter is made up of extremely small particles that are always moving (atoms and molecules) with spaces between them
•The particles are close together and slowest moving in solids, and farthest apart and fastest in gases
•Heat makes the particles move faster
Changes of State of Matter
sublimation
GAS
LIQUID
SOLID
solidification melting
sublimation
condensation evaporation