# Test 1 – Chemistry Flashcard

 Law of multiple proportions
 If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.Another way to say this is:A law proposed by Dalton which states that when elements combine, they do so in the ratio of small whole numbers. For example carbon and oxygen react to form CO or CO2, but not CO1.8.
 Law of Multiple Proportions

 The law stating that a pure substance, e.g. H2O, will always have the same percent by weight, e.g. 11.2% H  and 88.8% O.

 proton
 p+ or p in nucleus positive charge number defines atom number above symbol on periodic table
 neutron
 n neutral in nucleus purpose is to be mass in atom
 electron
 e- orbit around the nucleus negative charge
 neutral atom
 all stable atoms number of protons (p/p+) is equal to number of electrons (e-)
 atomic number
 Z  number of protons (p/p+) number above the symbol on the periodic table
 atomic mass number
 A weight of the atom number of protons + the number of neutrons
 isotope
 literally: same type same element, different mass due to different number of neutrons
 symbol
 eg: ^1H  abbreviation used to represent an atom on the periodic table the number to the upper left of the symbol is the mass number
 ion
 atom with unequal ratio of protons (p/p+) and electrons (e-) can be positively charged or negatively charged
 light
 has both wave properties and particles visible light is only a small part of the spectrum  [image][image][image]
 wavelength
 symbol: ___ the distance between 2 crests
 amplitude
 symbol: A the maximum displacement from the mean position
 frequency
 symbol: v the number of crests that pass a point per second  higher frequency means shorter wavelengths purple is the highest frequency, while red is the lowest
 photons
 particles that make up a stream (wave) of light energy of the photons is related to the frequency of the waves: E=hv (energy (E) = Plank’s Constant (h) x frequency (v);
 ;;;energy of photons in relation to; speed
 v= c/__ (velocity = velocity of light/ wavelength);;
 ;;;velocity of light;
 in the equation v = c/___ (wavelength);c = 3.00 x 10^8 m/s;
 ;;;Planck’s Constant
 h as in the equation: E = hv h = 6.63 x 10^-34 j/s
 Bohr Theory
 electrons (e-) have discrete energy levels e- are in orbits and that have specific energies this explains light absorption and emission  early theory of atomic structure explains postion of e- in relation to the nucleus only performed on H (hydrogen)  the farther away from the nucleus the e-, the energy level
 Quantum Mechanical Model
 replaced Bohr’s model because Bohr’s only worked for a few atoms because (he used hyrogen) -e (electrons) can be found anywhere within a shell, not just in a ring each -e (electron) is associated with a set of 4 quantum numbers
 Principal Quantum Number
 n   labels the energy levels of hydrogenic atoms. It is the first in a set of numbers that show the unique quantum state of an electron
 Pauli exclusion principle
 For electrons in a single atom, it states that no two electrons can have the same four quantum numbers, that is, if n, l, and ml are the same, ms must be different such that the electrons have opposite spins.
 Angular Momentum Quantum Number
 l (cursive) a quantum number for an atomic orbital which determines its orbital angular momentum
 Magnetic Quantum Number
 ml (cursive, lowercase "l") describe the unique quantum state of an electron denotes the energy levels available within a subshell
 Spin Quantum Number
 Ms parametrizes the intrinsic angular momentum (or spin angular momentum, or simply spin) of a given particle
 n
 Bohr’s orbit;
 ;;;n + l rule;
 ;;;;e- (electrons) increase in energy as the sum of n+l increases;;e- closer to the nucleus have lower energy and those farthest from the nucleus have highest;
 ;;;Degenerate e- (electrons);
 ;;Have the same energy;
 ;;;Shell;
 ;;;a group of electrons in an atom all having the same; n ( principal quantum number)
 ;;;subshell;
 ;;;e- (electrons) of an atom with the same n + l;
 ;;;e- in same shell;
 ;;2 e- (electrons) having the same n, l, and ml are said to be in the same orbit;
 ;;;Classification of Orbitals;
 ;;;to make classification easier, orbitals are assigned letters based on the value of l (angular momentum quantum number)
 ;;;Values of l;
 s = 0p = 1d = 2f = 3
 ;;;Heisenberg’s Uncertainty Principal
 the statement that locating a particle in a small region makes the momentum of the particle uncertain, and conversely, measuring the momentum of a particle precisely makes the position uncertain only the probable location can be calculated
 Maximun number of e- (electrons) per orbital
 s = 2p = 6d = 10f = 14
 Orbital Diagrams
 e- orbitals are filled as per energy levels and the Pauli Exclusion Principle, the Aufbau Principle  and Hund’s Rule
 ;;;Pauli Exclusion Principle;
 ;;;no atomic orbital can contain more than 2 e-;if e- are in the same orbital, they must have opposite spin;
 ;;;Aufbau Principle;
 ;;e- go to the lowest energy level first, before filling another energy level;
 ;;;Hund’s Rule
 every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.