Chem midterm #1

Bonding ratio for metals increases from…

left to right

reactivity for metals increases from…

top to bottom

Reactivity for nonmetals increases from…

bottom to top

Mass increases from…

left to right and top to bottom

Bonding ratios for nonmetals increases from…

Right to left

Radius increases from…

right to left and top to bottom

Hardness (in metals) increases from…

bottom to top

Model

conceptual or mathematical representation of real-world things or processes

Elements have a unique number of…

Protons (z)

Isotopes have a unique # of…

neutrons

Average atomic mass

weighted average of isotope masses

Ions have an unequal number of…

protons and electrons

If # protons > # electrons, overall charge is…

Positive (cation)

If # protons < # electrons, overall charge is…

negative (anion)

F

force

k

Coulomb’s Law

q1 and q2

charges

R²

distance between charges

Coulomb’s Law

opposite charges attract, like charges REPEL, bigger charges = stronger forces, bigger distance = weaker force

Number of shells increases…

Down a column, but stay the same across a row

What do core electrons in inner shell do to valence electrons

repel valence electrons outward

Greater distance between electrons =

weaker attractions

Greater charge =

stronger attraction

Zeff

effective nuclear charge

Larger Zeff =

smaller radius

Number of valence electrons increases from…

left to right, but stays the same down a column

E-

electron

Metal + metal = which type of bonding?

metallic bonding

Metal + nonmetal = which type of bonding?

ionic bonding

Nonmetal + nonmetal = which type of bonding?

molecular covalent bonding

Nonmetal + nonmetal = which type of bond?

extended covalent bonding

Structure of metallic bonding

positive atomic cores with negatively charged “sea” of valence electrons

Structure of ionic bonding

metal atoms give up valence electrons to become ions with net positive charge; nonmetals steal valence electrons to become ions with net negative charge

Structure of molecular covalent bonding

Positively charges atomic cores; valence electrons shared in covalent bonds between two atoms creating molecules

Structure of extended covalent bonding

positively charged atomic cores; valence electrons shared in covalent bonds between atoms

Properties of metallic bond

bendable, malleable, does not dissolve, conducts dry

Properties of molecular covalent bond

gases/liquids/soft solids, many dissolve, does not conduct

Properties of ionic bond

hard but brittle, many dissolve, solution conducts

Properties of extended covalent bond

rigid, difficult to break, does not dissolve, does not conduct

Covalent

bond in which valence electrons are shared

Ion

Number of protons not equal to number of electrons

Metal

element on left of table

Molecule

cluster of atoms sharing valence electrons

Nonmetal

element on right of table

Having _ or _electrons in the valence shell is stable

2 or 8

Noble gas envy

atoms gain or lose electrons to fulfill their noble gas envy

Ionic solids

charged ions combine to make neutral solids

How do you determine a molecule’s molecular formula?

find charge on each ion, cross charges down, and simplify

Polyatomic ions

chunk of atoms that stay together as a unit

Superscripts show…

charge

Subscripts show…

Amount of the element right before it in formula

Subscripts outside of parentheses in molecular formulas apply to…

everything inside

Charges in molecular formulas are omitted when…

ions combine to form neutral solids

Why are ionic solids likely to break, snap, or crack?

when like charges get too close, atoms fly apart

What in represented by the number in the top left corner of element on periodic table

Atomic number (# of protons)

What in represented by the number in the top right corner of element on periodic table

Ionic charge

What in represented by the number on the bottom of element on periodic table

atomic mass

Metals are more likely to…

lose electrons and become cations

Nonmetals are more likely to…

gain electrons and become anions

Nonmetals share…

Electrons

Transition metals are more likely to…

lose electrons and become positive

Nonmetals + nonmetals = ?

no charge bc of covalent bond (shared electrons)

super script of singular element/isotope = ?

number of protons + number of neutrons

HONC 1234

Bonding ratios: H - 1, O - 2, N - 3, C - 4

Where do H atoms go in Lewis structures and how many bonds can they have?

on the ends; one bond

Isomers

have the same molecular formula but different structural formula

The true nature of the molecule is…

a weighted average of the resonance contributors

How do you find bond order?

Number of bonds/number of regions

ideal gas law assumes…

particles have no interactions and no volume

Relationship between temperature (k) and avrg KE

directly proportional positive relationship (as temp increases, KE increases)

Relationship between temp (k) and average v

v generally increases with T

Relationship between temp (k) and volume (L)

Directly proportional positive relationship (as temp increases, volume increases)

Relationship between temp (k) and pressure (atm)

directly proportional positive relationship (as temp increases, pressure increases)

Formula for temp vs. volume

V = kT (K = C° + 273.15 K)

formula for temp vs pressure

P = kT (P = collisions w walls)

Relationship between volume (L) and pressure (atm)

inversely proportional (as volume increases, pressure decreases)

Relationship between # of particles (mol) and pressure (atm)

directly proportional positive relationship (as particles increase, pressure increase)

Relationship between # of particles and volume (L)

directly proportional (as particles increase, volume increases)

Formula for particles vs pressure

P = kn (in rigid container)

formula for particles vs volume

V = kn (in flexible container)

Ideal gas law formula

PV = nRT

In mixtures of gases…

Treat each gas independently

Partial pressure formula

P total = P + P (P = pressure from PV = nRT of each gas)

m

Mass (g)

P

pressure (atm/Pa/bar/torr)

T

temperature (C or K)

n

Number of particles (mol)

R

gas constant (0.08206 Pa L/mol K)

V

Volume (L)

v

Velocity (m/s)

What happens to pressure when volume of gas is high and they get compressed?

P (real) = P (ideal) because particle are too far apart to experience attractions (KE wins)

What happens to pressure when volume of gas is low and they become compressed?

P (real) < P (ideal) because attractions keep particles closer together and less likely to collide w walls (PE wins)

The real gas law

(P + a(n²/V²) x (V - nb) = nRT

What does a(n²/V²) represent in real gas law?

Attraction

What does nb represent in real gas law?

Volume

What does the ideal gas law assume?

that the molecules are not attracted to each other and that they have no volume

What happens to the volume when gases are at a high temp?

V (real) = V (ideal) because high kinetic energy outweighs potential energy

What happens to the volume when gases are at a med temp?

V (real) < V (ideal) because attractions keep particles closer together

What happens to the volume when gases are at a low temp?

V (real) > V (ideal) because nonzero particle size precludes V = 0

In order for a liquid to become a gas (vaporization) the liquid molecules must…

overcome attractions and external pressure