Chemistry Flashcards
Significant Figures
A way of showing how many digits to include in an answer. to find out the number of sig figs, start at the first nonzero number, and count until the end
Dimensional Analysis
A method of using one or more conversion factors to convert an item of one unit into that same amount of another unit.
Mass Number
The number of protons and neutrons in an atom
Atomic Number
The number of protons in an atom
Molar Mass
The mass of an element or compound in grams that would be in 1 mole of that element or compound
Mole
A mole is an easier way to count atoms by using Avogadro’s Number (1 mole = 6.022 * 10^23 atoms/units)
atom
smallest particle of an element that retains the chemical characteristics of that element
element
substance that cannot be separated into simpler substances by a chemical process
compound
substance composed of characteristic proportions of two or more elements chemically bonded together and can be separated by chemical processes into component elements
mixture
differs from a compound by the fact that a mixture can be separated into its components by physical and chemical methods (ex: salt and water are both compounds, but saltwater is a mixture)
homogeneous mixture/solution
all the components are uniformly distributed and the appearance is consistent throughout the sample
heterogeneous mixture
mixture where the composition is not uniform and the appearance may be inconsistent
intensive properties
independent of the amount of substance present (color, odor, malleability, density, temp etc)
extensive properties
dependent upon amount of substance (mass, volumes)
physical properties
properties that can be measured or observed without changing the substance (melting point, temperature, density)
chemical properties
property that describes how much a substance will react; the substance will change into a new substance from this property (oxidation, flammability)
law of definite proportions
principle that compounds always contain the same proportion of their component elements. An equivalent law is the law of constant composition that no matter the source of a compound, it will have the same elemental composition.
nucleus
positively charged center of the atom containing nearly all of the mass of an atom. consists of protons and neutrons
proton
positively charged subatomic particle
neutron
electronically neutral subatomic particle
electron
negatively charged subatomic particle
isotope
atoms of an element containing the same # of protons but different number of nuetrons
cathode ray experiment
identified a negatively charged particle that was emitted from an electrode in a cathode ray tube, an evacuated glass tube with the cathode connected to the negative terminal of a power supply.
The particles consistently deflected under the influence of electric or magnetic fields, indicating that the particle was negatively charged.
Rutherford Experiment (gold foil)
Rutherford attempted to validate the plum-pudding model by bombarding a gold foil target with alpha particles from a radioactive source.
The trajectory of the particles could be determined by observing phosphorescent images created by the collision of particles with a phosphorescent screen around the target.
precision
how repeatable a measurement is
accuracy
how close the measurement is to the true value
law of conservation of energy
states that energy cannot be created or destroyed, but it can be converted from one form to another
cation
A positively charged ion
Anion
A negatively charged ion
wavelength
the distance from crest to crest on a wave (m)
frequency
number of crests of a wave that pass a stationary point of reference per second (1 Hz = 1 s-1)
ground state
when an electron is in the lowest energy level
excited state
A state in which an atom has a higher potential energy than it has in its ground state
orbital
the space within an atom where the probability of finding an electron is very high
principal quantum number
(n) a positive integer that indicates the relative size and energy of an orbital in an atom
angular momentum quantum number
(ℓ) an integer with a value ranging from 0 to (n-1) and describes the shape of the orbital
magnetic quantum number
(mℓ) has values from -ℓ to ℓ, including zero; tells orientation of the orbital relative to other orbitals
spin quantum number
(ms) can only be 1/2 or -1/2 and describes the direction that an electron is spinning
Aufbau Principle
An electron occupies the lowest-energy orbital available
valence electrons
the outer most electrons, the electrons involved in bond formation
Hund’s Rule
orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin
