Chem Intro

Question 1

Element

Answer 1

Substances that cannot be broken down by chemical reactions

Question 1

Trace Element

Answer 1

Elements required in minute amounts but their lack can lead to severe problems

Question 2

Elements of Life

Answer 2

~25 elements make up life: Most are trace elements

Major elements: CHNOPS

Question 3

Atoms

Answer 3

Smallest unit of matter that retains the properties of an element

Question 4

Dalton

Answer 4

Mass of neutrons and protons

Question 5

Atomic Mass

Answer 5

Mass of neutrons + protons

Question 6

Atomic #

Answer 6

of protons: Unique for all elements

Question 7

Mass #

Answer 7

neutrons + # protons

Question 8

Isotope

Answer 8

Forms of the same elements with different # neutrons

Question 9

Radioactive Isotopes

Answer 9

Isotopes that undergo decay

Question 10

Covalent Bonds

Answer 10

2 types:

Polar = unequal sharing of electrons
(dipoles created by differences in electroneg.)

Non-Polar = equal sharing of electrons (equal electroneg.)

Question 11

Ionic Bonds

Answer 11

Electrons are transferred

Question 12

Weak Bonds

Answer 12

1) Hydrogen Bonds
2) Van der Waals Forces

Question 13

H-Bonds

Answer 13

A non-covalent attraction between a hydrogen and very electroneg. atom (usually O or N)

Question 14

Van der Waals Forces

Answer 14

Essentially the dispersion force: Attraction due to temporary dipoles formed due to electron movement

(Allows for temporary interactions)

Question 15

Acid

Answer 15

A substance that increases the H+ concentration of a solution

(Ex: HCl)

Question 16

Base

Answer 16

A substance that reduces the H+ concentration of a solution

–> Usually by increasing OH- conc.
(Ex: NaOH)

Question 17

pH Scale

Answer 17

A logarithmic scale: Numerical method for expressing the range of H+ concentrations

Question 18

pH Unit

Answer 18

Each pH unit or number is a 10x change in H+ concentration

Question 19

pH 7

Answer 19

Neutral pH

H+ = OH-

Question 20

pH < 7

Answer 20

Gets more acidic as you approach zero

H+ > OH-

Question 21

pH > 7

Answer 21

Gets more basic as you approach 14

H+ < OH-

Question 22

Difference between pH 3 and pH 6

Answer 22

pH 3 is 1000X more acidic than pH 6

Question 23

Buffer

Answer 23

A solution that contains weak acid and its corresponding base

–> Minimizes changes in pH when acids or bases are added to the solution (by donating H+ when depleted or accepting H+ when in excess)

Question 24

Molarity

Answer 24

mol solute / L solution

Question 25

Mole

Answer 25

Amount of substance equal to its molecular weight in grams

Question 26

Molecular Weight

Answer 26

Sum of weights of all the atoms in a molecule

Question 27

H3O+

Answer 27

Hydronium Ion:

H+ never exists in aqueous solutions but instead exists as hydronium

Question 28

Dissociation of Water

Answer 28

Water can dissociate into H+ and OH- but it is extremely rare: Helps to maintain the balance of H+ and OH- ions

–> Why it is the solvent of life