Chem 108 Exam 2

Chemical bonds need in order to share, gain and lose electrons is to

follow octet rule

Ionic bonds occur

when the atoms of one element lose valence electrons and the atoms of another element gain valence electrons

covalent bonds

occur when nonmetal atoms share electrons to attain a noble gas arrangement

metals are which groups

group 1A, group 2A, group 3A

metals have and are

• low ionization energies

• readily lose one or more of their valence electrons to form ions with a positive charge = cations

• lose electrons until they have the same number of valence electrons as the nearest noble gas usually eight valence electrons

nonmetals groups are

group 5A, group 6A, group 7A

nonmetals are and have

• have high ionization energies

• readily gain one or more valence electrons to form ions with a negative charge in ionic compounds = anions

• gain electrons until they have the same number of valence electrons as the nearest noble gas, usually eight valence electrons

ionic compounds

• consist of positive and negative ions

• have attractions called ionic bonds between positively and negatively charged ions

• have high melting points

• are solid at room temp

• attract each other to form an ionic compound

  • cations are written before anions

polyatomic ions are

ions that are made up of more than one atom. consist of nonmetals

molecular compounds form

• when atoms of two or more nonmetals share electrons and form a covalent bond

• valence electrons are shared by nonmetals atoms to achieve stability

double bond

• occurs when atoms share two pairs of electrons

• forms when there are not enough electrons to complete octets

triple bond

• occurs when atoms share three pairs of electrons

• forms when there are not enough electrons to complete octets

to know if its ionic or covalent ionic shows

first element in the formula or the name is a metal or polyatomic ion

to know if its ionic or covalent, covalent shows

first element in the formula is a nonmetal

polar covalent bonds

• atoms of some elements are able to attract electrons in a bond stronger than others

• polar bonds occur when electrons are shared unevenly

electronegativity

measures the attraction of an element for electrons

• high electronegativity = more attraction

nonpolar molecules

bonds that can not be paired

the mole equals to

avogadro’s number = 6.02 × 10²³

in a balanced chemical equation

• no atoms are lost or gained

• number of atoms on reactant side is equal to number of atoms on product side for each element

• to determine if an equation is balanced count the number of atoms of each element on each side of the equation

combustion reaction is

• energy is released as a product in the form of heat

• C4H10 + O2 → CO2 + H2O

combination is

A + B → AB

Two or more reactants, combines to yield a single product

Single replacement

A + BC → AC + B

One element replaces another element

Decomposition

AB → A + B

A reactant splits into two or more products

Double replacement

AB + CD → AD + CB

Two elements replace each other

oxidation

• always involves a loss of electrons

• seen as addition of oxygen

• may also be seen as loss of hydrogen atoms

reduction

• always involves a gain of electrons

• seen as loss of oxygen

• gain of hydrogen

law of conservation of mass

• matter cannot be created or destroyed

• no change in total mass occurs

• mass of products is equal to the mass of reactants

collision

reactants must collide

orientation

reactants must align properly to break and form bonds

energy

collision must provide the energy of activation

exothermic reaction

• heat is released

• energy of the products is less than the energy of the reactants

• heat is a product

endothermic reaction

• heat is absorbed

• the energy of the products is greater than the energy of the reactants

• heat is a reactant (added) (on left side of arrow)

reaction rate

• speed at which reactant is used up

• speed at which product forms

• increases when temps rises because the reacting molecule move faster, providing more collisions between molecules with energy of activation

• increases with increase in concentration of reactants

catalyst

• increases the rate of a reaction

• lowers the energy of activation

• is not used up during the reaction

• biological catalyst are proteins called enzymes

Kinetic Molecular theory

• move rapidly in straight lines

• have essentially no attractive (or repulsive) forces

• are very far apart

• have very small volumes compared to the volume of the container they occupy

• have kinetic energies that increase with an increase in temp

Gases are described in terms of four properties

• pressure

• volume

• temp

• amount

inspiration

• process of taking in air, diaphragm contracts and rib cage expands thus increasing the thoracic cavity

expiration

• process of exhaling air, diaphragm relaxes and rib cage contracts thus decreasing the thoracic cavity

solutions are

homogeneous mixtures of 2 or more substances

• form when there is sufficient attraction between the solute and solvent molecules

• two components the solvent, larger amount and the solute present in a smaller amount

solutes are

• may be liquids gases or solids

• are spread evenly throughout the solution

• mix with solvents

• cannot be separated by filtration but can be separated by evaporation

• not visible but can give a color to the solution

water

• is one of the most common solvents in nature

• is a polar molecule because of polar O-H bonds

• molecules form hydrogen bonds important in many biological compounds

strong elctrolytes

• dissociate 100% in water, producing positive and negative ions

  • form solution that conduct an electric current strong enough to light a bulb

weak electrolyte

• dissociates only slightly in water

• forms a solution with a few ions and mostly ions from undissociated molecules

nonelectrolytes

• dissolve as molecules in water

• do not produce ions in water

• do not conduct an electric current

Solubility

maximum amount of solute that dissolves in a specific amount of solvent

unsaturated solution

we can dissolve more solute

saturated solution

we have attained maximum solubility limit

insoluble

solubility is less than 1g/L

soluble

solubility is generally at least 10g/L

solubility depends on

temperature and pressure

solubility of a solid in water increase as you

raise the temperature

gases dissolve better in

cold water than in hot water

solubility of any gas

increases as you increase the pressure of the gas

not all ionic compounds, salts are

soluble in water

dilution is

process of adding water to reduce the solute concentration

volume and concentration are related by

inverse proportion, if you increase one you decrease the other

stock solution

is a concentrated solution of known concentration that will be diluted for use

solutions are

transparent do not separate and contain small particles ion or molecules that cannot be filtered and pass through semipermeable membranes

colloids have

medium size particles cannot be filtered and can be separated by semipermeable membranes

suspensions are

heterogeneous non uniform mixtures have very large particles that settle out of solution can be filtered

diffusion

• net movement of molecules from a higher concentration to a lower concentration

• will find equilibrium

osmosis

net movement of water through a semipermeable membrane

• when the concentration of solutions on the two sides of the membrane are different, osmosis will occur

osmotic pressure is equal

to the pressure that would prevent the flow of additional water into the more concentrated

pressure is greater

as the number of dissolved particles in the solution increases

tonicity

• relationship between overall concentration of the solution and the normal solute of concentration in blood cells

isotonic

solutions contain equal concentration that that of blood cells

hypertonic

solutions contain higher solute concentration that that of blood cells (crenation)

hypotonic

solutions contain lower solute concentration than that of blood cells (hemolysis)

dialysis

• net movement of solute particles through a membrane from higher concentration to lower