The law of conversation of mass
no changes can be observed in the total mass of all substances involved in a chemical reaction
law of definite proportions
some particular chemical compound always contains exactly the same proportion of chemical elements by mass
law of multiple proportions
if two elememts form more than one compuond between them, then the rations of the masses of the second element which combine with a fixed mass if the first element will be rations of small whole numbers (1:2:3)
equivalent weights
the masses of elementary substances with which they enter into chemical reactions
the ratio by weiht of the compounds consumed in a chemical reaction is always the same
Atomic theory
Atomic nucleus consists of
Protons (+) charge -> +1.6 x 10-19 C
Neutrons (0) charge -> 0
Mass of protons =
mass of neutrons
Number of protons =
Number of neutrons
Atomic number Z
number of protons or electrons
Mass number A
Number of protons + neutrons (number of nucleons)
Isotope
same number of protons, different number of neutrons
Atomic mass determined by
mass spectrometry
Mole
amount of a substance that contains as many elementary entities as there are atoms in 12g of pure carbon -12
S-orbital
Spherically-symmentric
the probability of electron density decreases moving away from the nucleus
1s orbital is closer to the nucleus and has a lower energy than 2s orbital
Maximal 7s
P-orbitall
Second quantum state
wave equation has THREE SOLUTIONS
electron density is equal on both sides of the nucleus -> there are 2 lobes
D-orbital
Starts with 4d
3rd quantum state
F-orbital
4th Quantum state
The size of an orbital depends on
the charge of the nucleus:
higer charge -> lower volume
in one orbital you can find
2 electrons of opposite spin
Main elements
fill s and p orbitals
transition elements
fill d orbitals
innner transition elements
fill f orbitals
7 periods
correspond to shells
18 groups
outer shells of the main elements have the same configureation
what is the second most stable configureation after nobel gases?
halfe filled orbitals
Atomic radius increases
downward because the numbers of shells increases
Atomic radius decreases
from left to right in each period because the force of the nucleus attraction and the number of electrons that come into the same chell increase
ionization energy
the energy required to remove an electron from an atom
in groups ionization energy decreases
downward because the radius increases and the nucleus attraction force weakens
in a period the ionization energy increases
from left to right because the radius decreases
Electron affinity
the amount of energy released or consumed when an electron is added to a neutral atom ot molecule to form a negative ion
In a group the Electron affinity decreases
downward and becomes less negative
in a period the Electron affinity increases
from left to right
What is the exeption to the rules of Electron affinity and ionization energy?
Stable configurations (nobel gasses) because it takes more energy to add electrons
Last changed2 years ago
