-
What is chemistry?
The study of matter.
-
Rules for sig figs (5)
- 1. Nonzero are always sig figs
- 2. Zeroes at beginning are never sig
- 3. Zeroes between non zero are always
- 4. Zeroes at the end of a number with decimal are always sig
- 5. Zeroes at the end of a number with no decimal points may or may not be sig depending on exactness of the number.
-
Mass
Quantity of matter in an object.
-
What are the three states of matter?
Solid,liquid and gas
-
What s density?
Mass per unit volume
-
Specific gravity
Comparison of density with that of water.
-
Energy
Capacity to do work
-
Kinetic energy
Energy of motion-any moving object
-
Potential energy
Stored energy-drawn bow, water held bavk by dam
-
Specific heat
Amount of heat necessary to raise 1 gram of a substance by 1°C
-
Heat
A form of energy, measured in calories
-
Factor-label method
Units are multiplied and divided while crossing out unit labels. For conversions.
-
Scientific method
Testing of hypotheses and theories by collecting facts.
-
Chemical change
Substances are used up and others formed.
-
Physical change
Substances do not change their identity.
-
Pure substances
Fixed composition, cannot be further purified
-
Mixtures
Combination of two or more pure substances
-
Pure substances can be (2):
- Elements-cannot be subdivided by physical or chemical means
- Compounds-elements united in fixed ratios
-
Mixtures can be (2):
- Homogeneous matter-uniform composition throughout
- Heterogeneous matter-nonuniform composition
-
Atom
The smallest particle that retains the chemical properties of the element. The interaction among atoms accounts for the properties of matter.
-
Dalton's atomic theory (5)
- All matter is made up of tiny, indivisible particles called atoms
- All atoms of a given element have the same chemical properties.
- In ordinary chemical reactions, no atom of any element disappears or is changed into another element.
- Compounds are formed by the chemical combination of two or more different kinds of atoms. In a given compound, the relstive numbers of each type of atom are constant and most commonly expressed as integers.
- A molecule is a tightly bound combination of two or more atoms that act as a single unit.
-
Antoine lavoisier
- Evidence for dalton's theory-
- Antoine lavoisier discovered the law of conservation of mass-no matter can be eier created or destroyed.
-
Joseph Proust
Law of constant composition-any compound is always made up of elements in the same proportion by mass.
-
Monotomic, diatomic and polyatomic elements
How many atoms cling together-helium and neon are monatomic, oxygen contains two atoms in each molecule.
-
Diatomic molecules (7):
- Free atoms do not exist
- O2 oxygen
- H2 hydrogen
- N2 nitrogen
- F2 fluorine
- Cl2 chlorine
- Br2 bromine
- I2 iodine
-
Polyatomic elements
- O3 ozone
- P4 phosphorus (one form)
- S8 sulfur ( one form)
- Diamond-millions of carbon atoms
-
Atomic number
Z-number of protons in the nucleus
-
AMU
- Atomic mass unit-relative scale of masses of atoms
- 1 amu is 1/12 the mass of a carbon atom containing 6 protons and 6 neutrons
-
Particles and charges
- Proton +1
- Electron -1
- Neutron neutral
-
-
Mass number
Sum of the number of protons and neutrons in its nucleus. Electrons are so small they dont count
-
Isotopes
Determined by different number of neutrons. Has different mass number.
-
Atomic weight
Weighted average of the masses in amu of its isotopes found on earth. The weight is very close to its mass number because protons and neutrons have an approx mass of 1 amu
-
Dmitri Mendeleyev
Invented periodic table. Started by arranging elements in order of increasing atomic weight. He noted that certain properties occur periodically.
|
|
