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 

 

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

 

 

 

 

 

 

 

 

 

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 = 0
  • p = 1
  • d = 2
  • f = 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 = 2
  • p = 6
  • d = 10
  • f = 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.

Get instant access to
all materials

Become a Member