47 terms

Chemistry course 1

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3 subatomic particles in an atom
proton, neutron, electron
what determines an element?
atomic number
what is an atomic number?
The number of protons in an atom. Is the unique identifier of an element.
nuclei
plural of nucleus
what does the nucleus contain?
protons and neutrons
atom
The most discreet particle of matter that cannot be broken down further. Contains a positively charged nucleus with negatively charged electrons floating around it. The majority of atoms is empty space.
matter
anything that has mass and occupies space
the scientific method
1. Make observations/collect data
2. Formulate hypothesis
3. Test hypothesis
scientific models
1. Theory
2. Law
theory
a tested hypothesis that has been proven true - it gives an overall explanation of natural phenomenon
law
a summary of behavior - a generally observed behavior
units of mass
kg/g/mg/pg
length
m/cm/nm/mm
time
s
temperature
K(kelvin), Celsius, Fahrenheit
amount
mol
unit factor method
divide measurements by unit factors for conversion
Kelvin
K = C + 273.15
Celsius
C = K - 273.15
or
(Tf - 32DF)5/9 = Tc
Fahrenheit
Tf = Tc * 9/5 +32
Density
Density = Mass/Volume
or
g/cm^3
States of Matter
Liquid, Solid, Gas
Properties of Matter
Density, State
Mixture
combination of variable composition of pure substances
Homogeneous
visible indistinguishable/solution
Heterogeneous
visible distinguishable
Elements
pure substance that can't be broken down further
Compound/Molecule
combination of elements
Ex: H2O
Law of Conservation of Mass
Mass is neither created nor destroyed.
Law of Definite Proportion
A given compound always contains the same proportion of elements by mass. Example: Water is always H2O. It is never something like H2O2.
Law of Multiple Proportions
When two elements form a series of compounds the ratio of masses is always reduced to a series of small whole numbers.
Dalton's Atomic Theory
1. Each element is made up of tiny particles called atoms.

2. Atoms of the same element are always identical.
Avogradro's Hypothesis
Different gases contain the same number of particles in the same volume, pressure or temperature.
Nucleus
Dense center of an atom that is positively charged. Contains the majority of the mass of an atom.
Electron
Negatively charged, not in the nucleus. Has a mass close to zero.
Protons
Positively charged, in the nucleus. Has a mass close to one.
Neutrons
Neutrally charged, in the nucleus. Has a mass close to one.
Isotope
Atom with a different number of neutrons but the same number of protons and electrons.
Atomic Weight
Example: Oxygen

Mass:
Oxygen
Proton = 1 8*1=8
Neutron = 1 8*1=8
Electron = 0 8*0=0
8+8=16
Atomic Weight = 16
Chemical Bond
Atoms come together to form molecules through bonds.
Covalent Bond
When two elements bond while sharing electrons.
Chemical Formual
Examples:
H2O
CH4
NH3
Ions
Charged atoms or molecules.
How to create ions?
You charge an atom by changing the number of electrons.
Anion
Negatively charged ions. When there are more electrons than protons.
Cation
Positively charged ions. When there are more protons than electrons.
Lesson two 40:00
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