atomic structure & molecular structure Flashcards
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*
