what do atoms contain?
-protons (positively charged)
-neutrons (uncharged)
-electrons (negatively charged)
-0.1% of the atoms volume is occupied by it nucleus
what are isotopes?
-atoms with the same atomic number but different mass number
what is Pauli’s exclusion principle?
-it states that each electron in an atom has a unique set of quantum numbers
what is covalent bonding?
-when atoms are the same and the nuclei share the electrons equally
what causes a polar covalent bond?
-when atoms are different and there is an unequal sharing of bonding electrons
what is the most electronegative and electropositive elements?
-electronegative=flourine
-electropositive=caesium
how do you calculate a dipole moment?
charge,Q (C) x distance between charges, d (m)
what do dipole moments depend on?
-electronegativity difference
-shape
what does VSEPR stand for?
-valence
-shell
-electron
-pair
-repulsion
what does the VSEPR theory suggest?
-it considers that molecular shape is determined primarily by the repulsions between pairs of electrons in the molecule
what characteristics make a compound linear?
-no of sets of electron pairs on the central atom=2
-no of lone pairs on central atom=0
-angle=180*
-example=CO2
what characteristics make a compound trigonal planar?
-no of sets of electron pairs on central atom=3
-no of lone pairs on central atom=0
-bond angle=120*
-example=boron trifluoride
what characteristics make a compound tetrahedral?
-no of sets of electron pairs on central atom=4
-no of lone pairs on central atom=0
-bond angle=109.5
-example=methane
why characteristics make a compound trigonal pyramidal?
-no of sets of electron pairs on central atom=4
-no of lone pairs on central atom=1
-bond angle=107*
-example=ammonia
what characteristics make a compound bent?
-no of sets of electron pairs on central atom=4
-no of lone pairs on central atom=2
-bond angle-105*
what is Aufbau’s principle?
it states that we build up the ground state (most stable) electron configuration of the atom starting with the orbital of lowest energy so each electron occupies the most stable available orbital
order of filling atomic orbitals
1s 2s 2p 3s 3p 4s 3d
what is hund’s rule?
-The lowest energy configuration involving orbitals of equal energies (e.g., 2px, 2py and 2pz) is the one with the maximum number of electrons in the same spin orientation… all ↑ or all ↑↓
what is the principle quantum number?
a positive interger,it determines size
what is the azimuthal quantum number?
-0 or a positive integer,it determines angular momentum
what is the magnetic quantum number?
-an integer between +1 and _1,it determines directionality
what is the spin quantum number?
-it is either +1/2 or -1/2 and it determines spin
how many atomic orbitals are there for the s,p,d and f atomic orbitals?
-s=1
-p=3
-d=5
-f=7
