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