Chemistry notes Essay

Submitted By Lukelightfoot
Words: 1585
Pages: 7


Matter that has a uniform and unchanging composition

Physical properties
Appearance: size shape color texture
Luster: appearance on surface shiny?
Conductivity: ability to move heat or electricity
Malleability: ability to be rolled or hammered into sheets
Ductility: ability to be drawn into a wire
Density:mass per unit volume
Boiling point: temp at which liquid changes to gas
Freezing point: temp at which liquid changes to solid
Phase under standard conditions

Extensive and intensive properties
Density: mass per unit of volume
Mass length volume
Extensive properties are dependent upon the amount of substance present
Intensive properties are independent of the amount of substance present

Chemical properties of matter
The ability of the substance to change into something else examples iron rusting or food cooking

States of matter
Solids definite volume and shape liquids definite volume but not shape gas no definite volume or shape plasma found in lightning

Matter can be a mixture or a pure substance
A mixture can be homo or heterogeneous
Pure substances can be elements or compounds
Compounds are chemically combined atoms and chemically combined atoms can be broken down into simpler substances by chemical means
Elements are pure substance that cannot be separated into simpler substances by physical or chemical means common elements are oxygen
Hydrogen, carbon, and sulfur

Filtration: a technique that uses a porous barrier to separate a solid from liquid
Distillation: based on the differences of boiling points of the substances
Crystillation: a technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance
Chromatography: a technique based on the tendency of a substance to be drawn across the surface of another material

Law of definite proportions
This law states that regardless of the amount a compound is always composed of the same elements in the same proportion by mass

Law of multiple proportions
This law states that when different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers

Atomic theory 1.1
History of the atomic theory
Democritus(c. 460-c.370 BC) thought they were indivisible
Antoine Lavoisier (1743-1794)
Joseph Proust (1754-1836)
John Dalton (1766-1844)
1 each element is composed of tiny particles called atoms.
2 all atoms of a given element are identical, and all atoms of different elements are different
3 atoms are not created or destroyed in chemical reactions. They dissociated, combined, or recombined m
Good conductors
Non metals
Poor conductors
Semi conductors
Elements in a group have similar physical and chemical properties
Group 1 alkali metals
Group 2 alkaline earth metals
Group 3 halogens
Group 4 noble gases

Atomic theory 1.2
Average atomic mass
Protons charge +1 mass 1
Electron -1 .0005 mass
Neutron 0 1 mass
Atomic and mass numbers
Mass number equal to the number of protons plus the number of neutrons
Atomic number the number of protons
Isotopes of an element have the same number of protons but different number of neutrons
Isotopes of an element exhibit identical chemical behavior
This is why hydrogen and hydrogen squared will both bond with oxygen to form water
Carbon -14 and carbon -12 bond with oxygen to form CO^2
Atomic masses
The mass of one 12^atom is exactly 12 amu
All other atoms are measured on a scale relative to C12
Ex1 average atomic mass
The atomic mass given to you on the periodic table is an average of all the isotopes of that element
To find the average atomic mass of silver you must multiply the mass of each isotope by the decimal equivalent if its percent