Chemistry

Matter
Anything that occupies space and can be perceived by our senses
Law Of Conservation Of Mass
The total mass remains constant during a chemical reaction
Physical Change
A change in the form of matter but not in its chemical identity
(Tearing paper…)
Chemical Change/Reaction
A change in which one or more kinds of matter are transformed into new matter or several new kinds of matter
(Burning paper…)
Physical Property
A characteristic that can be observed with out changing its chemical identity
(Melting point, state of matter, color…)
Chemical Property
A characteristic of a material involving its chemical change
(Reactants, flammability, conductivity…)
Pure Substance
A kind of matter that cannot be separated into other kinds of matter by any physical process
(Sodium Chloride, water…)
Element
A substance that cannot be decomposed into simpler substances by any chemical reaction
(Oxygen, Hydrogen, Bromine…)
Compound
A substance composed of two or more elements chemically combined
(Water, table salt…)
Law Of Definite Proportions/ Multiple Proportions
A pure compound, whatever its source, always contains definite or constant proportions of the elements by mass
(1.0000g of sodium chloride always contains .3934g of sodium and .6066g of chlorine, chemically combined)
Mixture
A material that can be separated by physical means into two or more substances
(Evaporating salt water to get water and salt)
Heterogenous Mixture
A mixture that consists of physically distinct parts, each with different properties
(Salad, Coffee beans…)
Homogenous Mixture/Solution
A mixture that is uniform in its properties throughout given samples
(Finely ground sand, sugar water…)
Precision
The closeness of the set of values obtained from identical measurements of a quantity
Accuracy
The closeness of a single measurement to its true value
Significant Figures
(Sig. Figs)
Those digits of a number (or result of a calculation with measured numbers) that include all certain digits plus a final one having some uncertainty
Density
The mass per unit volume
(D=M/V)
Dimensional Analysis
The method of calculation in which one carries along the units for quantities
Conversion Factor
A factor equal to 1 that converts a quantity expressed in one unit to a quantity expressed in another unit
Atomic Theory
An explanation of the structure of matter in terms of different combinations of very small particles
Daltons Postulates
ATOM
All matter is composed of indivisible atoms. An ATOM is a extremely small particle of matter that retains its identity during chemical reactions
Daltons Postulates
ELEMENT
A type of matter is composed of only one kind of atom, each atom of the given kind having the same properties. Mass is one such property. Thus the atoms of a given element have a characteristic mass
Daltons Postulates
COMPOUND
A type of matter composed of atoms of two or more elements chemically combined in fixed proportions
(Water, H2O…)
Daltons Postulates
CHEMICAL REACTION
The rearrangement of atoms present in the reacting substances to give new chemical combinations present in substances formed by the reaction. Atoms are not created, destroyed, or broken into smaller particles by chemical reactions
Atomic Symbol
A one or two lettered notation used to represent an tom corresponding to a particular element
(Top # is ATOMIC #, Bottom # is MASS #
Electron
Very light, negatively charged particle that exists in a region around the atoms positively charged nucleus
Nucleus
The central core of an atom, contains most of the mass and is positively charged
Proton
Exists in the Nucleus and has a mass of 1 AMU, positively charged
Neutron
Exists in the Nucleus and is neutral in charge, has a mass of 1 AMU
Atomic Mass Unit
A mass equal to exactly 1/12 of the mass of a carbon -12 atom
Rutherford’s Experiment
According to his model 99.95% or more of the mass of the atom is concentrated in the positively charged nucleus.
Mass Number
The total number of protons and neutrons in a nucleus
Atomic Number
The number of protons in the nucleus of an atom
Isotope
An atom whose nuclei have the same number of protons but a different number of neutrons
Atomic Mass
The average atomic mass for the naturally occurring element, expressed in atomic mass units
Fractional Abundance
The fraction of the total number of atoms that is composed of a particular isotope
Mole
The quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12g or Carbon-12
(6.022 x 10^23)
Avogadro’s Number
The number of atoms in a 12g sample of Carbon-12
(6.022 x 10^23)
Thomson’s Model
Conducted experiments that showed atoms are not indivisible particles. By sending a negatively charged green light between a cathode and anode and saw the light being bent towards the positive plate as it was attracted
Frequency
The number of wavelengths of that wave that pass a fixed point in one unit of time
Wavelength
The distance between any two adjacent identical points of a wave
Visible Spectrum
Between 400nm and 800nm
ROYGBIV, the lower the nm in wavelength and higher frequency the darker the colour. The higher the no in wavelength and lower the frequency the lighter the colour.
Electro Magnetic Spectrum
The range of frequencies or wavelengths of electromagnetic radiation
Electron Absorption and Emission
Electrons can only change their state of energy when they receive work. when they are heated or get energy the move up in energy levels for a brief moment, and when they run out of energy after moving up, they fall back to ground state during their fall back to ground state is when the color is emitted, whatever color is emitted is the color that caused them to change energy levels in the first place