Chemistry

Question 1

Hund’s rule

Answer 1

states that electrons fill orbitals in a specific order, and they fill orbitals singly with similar spin before pairing

**Hund’s Rule. Hund’s rule: every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Question 2

Ionization energy is what?

Answer 2

energy necessary to remove an electron from a neutral atom in its gaseous phase

Question 3

Electronegativity is what?

Answer 3

how easily an atom can attract an electrons and form chemical bonds

Question 4

Melting point

Answer 4

amount of energy that is required to change the substance from a solid phase to a liquid

Question 5

solute, solvent, solution, heterogenous, homogeneous, mixture

Answer 5

…

Question 6

adhesive and cohesive

Answer 6

…

Question 7

ionic substances actively dissolve in water, why?

Answer 7

because the hydrogen and oxygen atoms in the H2O molecules have partial charges that attract the ions in the solid compound, causing it to dissociate into separated ions. Differences in electronegativity account for the partial positive charge carried by water’s hydrogen atoms and the partial negative charge of its oxygen atoms. What is happening to the ionic compound when it dissolves is a separation of its ions from their preexisting solid crystal lattice structure into unattached ions that are free to move about in the solution.

Question 8

tonicity

Answer 8

is a measure of the effective osmotic pressure gradient, as defined by the water potential of two solutions separated by a semipermeable membrane. In other words, tonicity is the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion. It is commonly used when describing the response of cells immersed in an external solution.
Unlike osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an effective osmotic pressure. Solutes able to freely cross the membrane do not affect tonicity because they will always be in equal concentrations on both sides of the membrane. It is also a factor affecting imbibition.

Question 9

hypertonic solution

Answer 9

those which have a higher concentration of a given solute than the interior of the cell. when placed in such solutions, the cell will lose solvent (water) as the solvent travels to area of higher solute in order to equalize concentrations

Question 10

hypotonic solution

Answer 10

solution that has a lower concentration of a given solute than the cell. water will enter the cell causing it to swell.

Question 11

isotonic solutions

Answer 11

those in which solute concentration equals solute concentration inside the cell

Question 12

what is plasma?

Answer 12

similar to gas, but contains free moving charged particles (although its overall charge is neutral).

Question 13

particles in gases, liquids and solids all do what?

Answer 13

vibrate

Question 14

is energy being absorbed or released when particles go from solid to liquid?

Answer 14

going to higher energy state so energy is being absorbed (endothermic rxn)

Question 15

is energy being absorbed or released when particles go from liquid to solid?

Answer 15

going to lower energy state so energy is being released (exothermic rxn)

Question 16

melting

Answer 16

solid to liquid

Question 17

freezing

Answer 17

liquid to solid

Question 18

condensation

Answer 18

gas to liquid

Question 19

evaporation

Answer 19

liquid to gas

Question 20

sublimation

Answer 20

solid to gas

Question 21

deposition

Answer 21

gas to solid

Question 22

lines of equilibrium on a phase diagram?

Answer 22

any point on this line represents a pressure and temperature at which multiple phases exist in equilibrium

Question 23

triple point on a phase diagram?

Answer 23

the point at which the lines of equilibrium intersect and all three phases (solid, liquid, and gas) exist in equilibrium

Question 24

critical point on phase diagram? supercritical fluid

Answer 24

the point at which the phase boundary b/w liquid and gas terminates. This represents the fact that at very high temp and pressure, liquid and gas phases become indistinguishable. This is known as a supercritical fluid

Question 25

law of conservation of matter

Answer 25

that matter is neither created nor destroyed in a chemical reaction

Question 26

decomposition reactions

Answer 26

common class of reaction consisting of the separation of a compound into atoms or simpler molecules: AB –> A + B

Question 27

single substitution reactions

Answer 27

part of one molecule is replaced by another atom or molecule – reactivity is determined by activity series

AB + C –> AC + B

Question 28

combustion reaction

Answer 28

when oxygen is used as a reactant and produces carbon dioxide and water – produces a great deal of heat

Question 29

exothermic reactions

Answer 29

produce energy

Question 30

endothermic reactions

Answer 30

use energy

Question 31

regardless of whether energy is absorbed or released overall, every chemical reaction requires a certain amount of energy to begin. this is called what?

Answer 31

the activation energy

Question 32

a number of variables influence the rate of rxn

Answer 32

temperature, pressure, concentration, and surface area