Chapter 1 Book Flashcards
Atoms
all matter is made of
describe an atom
Nucleus made of proton and neutrons and electron cloud surrounding nucleus
Atomic number
number of protons
Cation
+ charged with less electrons than protons
Anion
- charged more electrons than protons
Isotopes
2 atoms of same element with different number of neutrons
Mass #
atoms total number of protons and neutrons in nucleus
Atomic weight
particular element weight from average mass of isotopes
What is the common H isotope and what is it called
1 proton with no neutrons is called deuterium
periodic table
schematic arrangement arranged by increasing atomic number
group number
column of periodic table
properties similar in columns and rows
similar size
similar electronic and chemical properties
orbitals and what are they named
region of space that is high electron density spdf
Shape of S orbital
sphere
Shape of P orbital
dumbell shape
Common bonds of atoms
H 1 bond
C 4 bonds
N 3 bonds 1 lone pair
O 2 bonds 2 lone pairs
X 1 bond 3 lone pairs
How many electrons can S orbital have
2
How many electrons can p orbitals have
6
Valence electrons
outmost electrons that bond to atoms
Compounds
2 or more elements
Octet rule
8 Valence electrons wanted
Ionic bonds
transfer of electrons to another element
Covalent bonds
sharing electrons between 2 nucei
What do ionic bonds form
crystal lattices
What bonds form molecules?
Covalent bonds
Lone pairs
unshared electrons
lewis structures
electrons dots representation for molecules
formal charge
charge assigned to single atoms in lewis structures
Formula for formal charge
of VE- (unshared electrons+ 1/2 of bond electrons)
Isomers
more than 1 arrangement of atoms possible from same molecular formula
Constitutional isomers
same molecular formula but connectivity of atoms different
exceptions to the octet rule
H has 2 electrons
B and Be not enough electrons
P and S more than 8 electrons
resonance structures
2 lewis structures with same placement of atoms but different arrangement of electrons
double-headed arrow
separates 2 resonance structures
resonance hybrids
composite of both forms of resonance structures where electrons are delocalized and resonance stabilized
curved arrow notation
shows how electron positions differ
heteroatom
atom that is not C or H
major contributor
better resonance structure
minor contributor
not the better r structure
What makes a resonance structure better
more bonds fewer charges
Bond length
average distance between centers of 2 bonded nuclei
how does bond length decrease and increase and why?
bond length decreases across row as size of atom decreases
bond length increases down a column as size of atom increases
Bond angle
determines shape around any atom bonded
VSEPR theory
electron pairs repel each other
2 groups of electrons around atom
linear 180 degrees
3 groups of electrons around atom
trigonal planar 120 degrees
4 groups of electrons around atom
tetrahedral 109 degrees
discuss lines on a molecule
solid line is in plane
wedge is in front of plane
dashed is behind plane
trigonal pyramidal
tetrahedral with 1 lone pair 107 degrees
Bent
tetrahedral 2 lone pairs 105 degrees
condensed structures
All atoms bond lines omitted with parenthesis around similar groups with same atoms
Skeletal structures
C is junction of 2 lines or at end of a line with C having enough H
draw all heteroatoms
charges take place of H with lone pairs
sigma bond
cylindrically symetrical
ground state
lowest energy arrangement
hybridization
2 or more atomic orbitals form some # of hybrid orbitals
sp3
2s1 and 2p3
sp2
2s1 2p2
sp
2s12p1
pi bond
not concentrated on the axis and is weaker
Bond length vs bond strength
increase in bond length= decrease in bond strength
decrease in bond length= increase in bond strength
therefore short bonds are strong bonds
Joule
SI unit of energy
Calories
O chem energy value unit
Conversion of calories to Joules
1 cal= 4.18 J
percent S character
fraction of hybrid orbital
hybrid s characters percentage and why
sp is 1 2s/ 2 hybrid= 50% s characters
sp2 is 1 2s/ 3 hybrid= 33% s character
sp3 is 1 2s/ 4 hybrid= 25% s character
What happens to electrons as % s character increases and what about the bonds
As % s character increases, hybrid holds elections closer causing bonds to become shorter and stronger
Electronegativity and how it increases and decrease
measure of atoms attraction for electrons
increases across row of PT as nuclear charge increases
decreases down column of PT as atomic radius increases
Where is most electronegative element
upper right hand corner
dipole
partial sepration of charge
Polar bond
electronegativity difference between 2 atoms is very small
electrostatic potential map
distribution of electron density in a molecule where electron-rich area is red and electron-deficient is blue
What type of polarity is H2O and why
Polar because O is different than Hs
What type of polarity is CO2 and why
linear molecular cancels out polarity making it nonpolar
