Chemistry study guide for final: Unit 4 & Unit 5 Periodic table and Bonding
Which element has the greater atomic radii O or As?
As (Arsenic) Why? they get larger as you go down the group
tetrahedral
CH4 central atom bonded to 4 peripheral atoms and central atom has zero unshared electron pairs 109.5 degrees
tetrahedral
CH4 methane carbon is in center
nitrogen group
Group VA 5 valence electrons nitrogen is used in fertilizers and explosives nitrogen N, phosphorus P, arsenic As, antimony Sb, bismuth Bi
oxygen group
Group VIA 6 valence electrons oxygen, sulfur, selenium, tellurium, pollonium Note: oxygen is the most common element
halogens
Group VIIA exists in a variety of states at room temperature elements in this group are all one electron short of having a complete s-p octet in their outer energy level (fluorine F, chlorine Cl, Bromine Br, Iodine I, Astatine At) seven valence electrons
noble gases
Group VIIIA do not react with other elements chemically unreactive monoatomic gases: helium, neon, argon, krypton, xenon, and radon (He, Ne, Ar, Kr, Xe, Rn) eight valence electrons exception is helium that has only 2 valence electrons
Which element has the greater atomic radii H or N?
H Why? they get smaller as you go across a period
Tetrahedral (Bent) total electron domains = 4 pairs
H2O central atom bonded to 2 peripheral atoms and central atom has two unshared electron pairs. 105 degrees
IUPAC
International Union of Pure and Applied Chemistry labeled the groups from left to right with numbers (1 - 18)
SO2
S = nonmetal O = nonmetal answer = covalent
Octahedral
SF6
Which atom has a lower electron affinity? S or O
Sulfur, Why? Because Sulfur is located underneath oxygen on the periodic table
Tetrahedral (trigonal pyramidal) total electron domains = 4 pairs
You see lone pair in image to left
ionic bond
a chemcal bond formed when one or more electrons are transferred from one atom to another
metallic bond
a chemical bond formed by the attraction between positively charged metal ions and the electrons around them
covalent bond
a chemical bond formed when two atoms share electrons
molecule
a group of atoms held together by covalent bonds
electron sea
a model for the behavior of electrons in metals.
diatomic
a molecule that consists of two atoms of the same element.
anion
a negatively charged ion
bonding pair
a pair of electrons shared between two atoms
cation
a positively charged ion
ion
an atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge
ionization
any process that results in formation of an ion.
Elements that do not form compounds are not _____________ electronegativities. ex: noble gases
assigned
electronegativity
atom's ability to attract and hold electrons
Electronegativity is the tendency of an atom to _______ an electron
attract F = 3.98 O= 3.44 C = 3.18
rare earth metals
broken down into the actinides and lanthanoides
Which atom has a higher electron affinity? Mg or Cl? Electron affinity
chlorine, Why? chlorine is a halogen and halogens have highest electron affinities.
Lewis structure
diagram that shows bonding between atoms in a compound and the lone pairs of electrons similar to Lewis dot structure but also is going to contain lines to represent bonds.
structural formula
diagram that shows the arrangement of atoms without valence electrons
ionic radius
distance from the center of an ion's nucleus to its outermost electron
delocalized
electrons that are not confined to a particular location, but are able to move throughout a structure
groups are also known as
families each group has specific characteristics or traits in common elements are defined by the group they are in.
Which element is the most electronegative element?
fluorine value of 3.98
What are the three intermolecular forces?
forces of attraction between molecules hydrogen boding dipole-dipole london or dispersion forces
What are the three types of intramolecular forces?
forces of attraction within a molecule ionic bonds - strongest metallic bonds covalent bonds
Electron affinity trends
halogens have the highest electron affinities metals have characteristically low electron affinities electron affinity tends to increase across a period electron affinity tends to increase up a group
Ion size tends to_____________downward within a group.
increase
electronegativity
increase across a period decrease down a group of main group elements
What are the two types of forces?
intramolecular forces intermolecular forces
Anions are negative ions and they are ______ than the corresponding atoms.
larger (gained electrons)
It takes _______energy to break a long bond.
less
the periodic table is made up of mostly _______.
metals
ionization energy trends
metals have characteristically low ionization energies nonmetals have high ionization energies nobel gases have very high ionization energies
It takes _______energy to break a short bond.
more
Trends of electronegativities
nonmetals have characteristically high electronegativities Highest: is the upper right corner of periodic table Fluorine has highest value at 3.98 Metals have low electronegativities Lowest is found in lower left corner of the table Francium has lowest value at 0.70
atomic radius
one-half the distance between the nuclei of identical atoms that are bonded together
Which element has the greatest electronegativity? Li or O? (Lithium or oxygen)
oxygen, why? numbers get larger as you go across the periods metals have low electronegativities
nonpolar bond
results from an even charge distribution between atoms in a compound (electrons are evenly shared) O2
Polar bond
results from uneven partial charge distribution between atoms in a compound because electrons are unequally shared between atoms. ex: H2O and NH3
Cations are positive ions and they are ______than the corresponding atoms.
smaller (lost electrons)
octet rule
states that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
bond energy (enthalpy)
the amound of energy required to break a chemical bond and form neutral atoms
ionization energy
the amount of energy required to remove an electron from an atom
electron affinity
the change in energy of a neutral atom when an electron is added to the atom to form a negative ion (anion)
bond length
the distance between two bonded atoms
valence electrons
the electrons in the outermost shell of an atom; these are the electrons involved in forming bonds
ionization energy
the energy required to remove one electron from a neutral atom of an element forming a positive ion (cation)
Atomic radii
trends: atomic radius tends to decrease across a period due to increasing positive nuclear charge atomic radius tends to increase down a group due to increasing number of energy levels
non-bonding pair
two paired valence electrons that do not participate in a chemical bond, yet influence that shape of the molecule
carbon group
Group IV A 4 valence elentrons carbon C, silicon Si, germanium Ge, tin Sn , and lead Pb The element carbon is the basis of life.
PO4 -3
P = nonmetal O = nonmetal answer = covalent
trigonal bipyramid
PCl5
Trigonal bipyramid
PF5
Non-polar covalent bonds
0.0 - 0.3 bonding electrons are shared equally all 7 diatomic molecules (H2, N2, O2, F2, Cl2, Br2, I2) also assume C-C and C-H bonds are non-polar
Polar covalent bonds
0.4 - 1.7 the more electronegative atom attracts the shared electron pair more strongly than the less electronegative atom. ex: HCl
Rules for lewis structure study bonding basics in notebook examples page 113
1. count all valence electrons 2. draw the least electronegative atom in the center 3. draw single bonds to the center atom 4. complete the octets with the remaining electrons add 1 electron for each negative charge subtract 1 electron for each positive charge
Features of covalent bonds
1. formed when atoms share electrons 2. formed between nonmetal and nonmetal 3. weak bonds 4. The term molecule refers to two or more atoms held together by covalent bonds 5. Double bond = covalent bond where atoms share two pairs of electrons. 6. Triple bond = covalent bond where atoms share three pairs of electrons 7. Single bond = covalent bond where atoms share 1 pair of electrons by two atoms
Features of metallic bonds
1. high melting/boiling point 2. malleable: hammered into sheets ex: aluminum foil 3. ductility: made into thin wires ex: copper wires (Cu) 4. high electrical conductivity: delocalized electrons free to move around 5. thermal conductivity: heated electrons quickly move along a piece of metal 6. luster : delocalized electrons in metals readily absorb or capture light 7. formed between metals and metals 8. In a pure chunk of metal, the valence electrons are delocalized (they do not belong to any one single atom, but are free to move around) 9. All of these free electrons are shared, in a sort of electron sea.
Features of ionic bonds
1. results from the electrostative charge between oppositively charged particles. 2. hard and brittle soluble in water 3. transfers electrons 4. high melting/boiling point 5. formulaic unit 6. formed between nonmetal and metal 7. strongest bond 8. solid at room temp. 9. conducts electricity
Ionic bond
1.8 - 4.0 one atom completely loses its valence electrons and the other (more electronegative atom gains them) ex: NaCl
trigonal planar
120 degrees BF3 central atom bonded to 3 peripheral atoms and central atom has zero unshared electron pairs see page 121 of notebook Bent NO2 118 degrees central atom bonded to 2 peripheral atoms and central atom has 1 unshared electron pair
Linear
180 degrees CO2 diatomic or central atom bonded to 2 peripheral atoms and central atom has 0 unshared electron pairs
alkaline earth metals
Group IIA beryllium, magnesium, calcium, strontium, barium, radium (Be, Mg, Ca, Sr, Ba, Ra) two valence electrons not as reactive as group IA metals
Boron group
Group IIIA 3 valence electrons Boron B, aluminum Al, Gallium Ga, Indium In, Thallium Th
Transition metals
Group 3 - 12 d Block mallaeable conductors
alkali metals
Group IA lithium, sodium, potassium, rubidium, cesium, francium (Li, Na, K, Rb, Cs, Fr) one valence electron the MOST REACTIVE OF ALL THE METALS
Which atom has a lower ionization energy Li (lithium) or F (fluorine)?
Li, why? metals have very low ionization energies
MgBr2
Mg = metal Br = nonmetal answer = ionic
What kind of bond is seen in NO2?
N = nonmetal O = nonmetal answer= covalent
Tetrahedral trigonal pyramidal total electron domains = 4 pairs
NH3 central atom bonded to 3 peripheral atoms and central atom has one unshared electron pair 107 degrees
NaCl
Na = metal Cl = nonmetal answer= ionic
Which atom has a greater ionization energy Ne or Kr?
Ne Why? As you go up the group, the ionization energy increases
Valence Shell, Electron-Pair Repulsion
VSEPR