Post on 16-Feb-2016
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Chemistry Wrap-Up
Matter Matter is anything that has mass and
takes up space. Atoms are the smallest unit of matter
Subatomic Particles: Proton: positive Neutron: neutral Electron: negative
Nucleus: almost all mass, very dense, neutrons and protons, center of the atom
Matter An element is the smallest unit that can
be considered a pure form matter, single atoms are all of a specific element which is determined by number of protons
Two or more atoms can combine in specific ratios to form molecules
Elements and the Periodic Table There are a finite number of elements Elements on the periodic table are
grouped according to similarities of their properties.
Elements in the same family share similar characteristics
Combining Atoms The atoms of elements combine in ways
that make up everything in the universe.
It’s like Lego: you can build many different things with only 200 different blocks by combining different amounts of blocks in different ways.
Compounds, Elements, Mixtures, and SolutionsMixtures – two or more substances
that are not chemically combined with each other and can be separated by physical means. The substances in a mixture retain their individual properties. Solutions – a special kind of mixture
where one substance dissolves in another.
Compounds, Elements, Mixtures, and Solutions cont. Elements – simplest form of pure
substance. They cannot be broken into anything else by physical or chemical means.
Compounds – pure substances that are the unions of two or more elements. They can be broken into simpler substances by chemical means.
To classify matter: Is the matter uniform throughout? Can it be separated by physical means? Can it be separated by chemical means?
Molecular Motion Atoms and molecules move depending
on their amount of energy (heat) When there is more energy, atoms are
less attracted to each other and move faster
When there is less energy atoms are more attracted to each other and move slower
Phases of Matter The movement of molecules causes
matter to exist in three main phases: Solid: lowest energy Liquid: median Gas: highest energy
Properties of Matter All types of matter have specific
properties that are unique to that type of matter and are independent of the size of the piece of matter
Density A measure of how tightly packed the
molecules are in a piece of matter Density of 1g of gold is the SAME as the
density of 100g of gold. Density is independent of sample size D=m/v
Other Examples All of these properties values are
regardless of HOW MUCH of a sample you have
Conductivity: how well a substance moves heat or electricity
Solubility: how well something dissolves in water
Magnetic properties: how magnetic something is
pH pH (potential hydrogen) A measurement of how acidic or basic a
solution is Measured on a scale from 0-14 0-6: Acids 8-14: Bases 7: Neutral
Chemical Reactions Law of Conservation of Mass
Mass is conserved, the number of atoms reacting is the same as the number of atoms that make the product.
Physical v. Chemical Change Chemical Changes
The chemical make-up of the substance is different.
Color change, fire, new smell, precipitate Physical Changes
The substance is chemically the same Crumpling paper, ice melting
Temperature and Chemical Change A higher temperature will increase the
speed of a reaction A lower temperature will decrease the
speed This is because of the motion of the
molecules