Topic 2

Question 1

atom

Answer 1

the simplest unit of matter

extremely small particles consisting of varying number subatomic particles: electrons, protons, neutrons, and varying atomic number & mass

Question 2

elements

Answer 2

A substance that cannot be broken down into other substances by ordinary chemical procedures

Question 3

matter

Answer 3

Any substance in the universe that has mass and occupies space

Question 4

energy

Answer 4

Energy is needed by all living things to carry out life processes, such as breaking down and building up molecules, and transporting many molecules across cell membranes. It is also responsible for growth and development of a biological cell or organelle. It is carried in the molecule ATP. It is released when a new and strong chemical bond has formed.

Question 5

electron

Answer 5

subatomic particles with a negative charge, found in orbitals surrounding the nucleus

Question 6

proton

Answer 6

subatomic particles with a positive charge, found in the nucleus, a mass of ~ 1 Dalton

Question 7

neutron

Answer 7

subatomic particles with a neutral charge, largest subatomic particle, found in the nucleus, a mass of ~ 1 Dalton

Question 8

atomic number

Answer 8

will always be equal to the number of protons in the atom

Question 9

atomic mass

Answer 9

equal to the sum of the atom’s neutrons and protons

Question 10

ions

Answer 10

atoms with a positive or negative charge

Question 11

cations

Answer 11

atoms that develop a net positive charge because they lose electrons

Question 12

anions

Answer 12

atoms that develop a net negative charge because they gain electrons

Question 13

isotopes

Answer 13

variants of a chemical element that have the same atomic number, but different atomic masses and physical properties. This is because they have the same number of protons but different numbers of neutrons

Question 14

radioactive isotopes

Answer 14

are unstable and emit radiation as the nucleus breaks up

they lead to cell death in high doses and produce genetic mutations

Question 15

half-life

Answer 15

the time it takes for one-half of the atoms in a sample to decay.

rate of decay for a radioactive isotope

Question 16

valence electrons

Answer 16

is the number of electrons an atom/element contains in the outermost electron shell.

Question 17

octet rule

Answer 17

elements tend to bond in a way that their outer shell of electrons is full (especially C, N, O, & halogens)

Question 18

inert valence shell

Answer 18

(Nonreactive/noble) elements have their outer valence shell filled, contain all 8 electrons.

Question 19

chemical bonds

Answer 19

relationships of energy between electrons of the atoms involved

Question 20

ionic bonds

Answer 20

when one atom donates one or more electrons to another atom forming ions

Question 21

covalent bonds

Answer 21

involve sharing two or more valence electrons between atoms

Question 22

hydrogen bonds

Answer 22

weak intermolecular chemical bonds between a partially negative oxygen atom and the partially positive hydrogen atoms of water molecules

Question 23

polar covalent bonds

Answer 23

a type of covalent bond where the atoms involved have an unequal attraction for electrons, resulting in unequal sharing

Question 24

nonpolar covalent bonds

Answer 24

a type of chemical bond where the electrons are shared equally between two atoms

Question 25

electronegativity

Answer 25

an atom’s affinity for electrons, and the differences in electronegativity dictates how electrons are distributed in covalent bonds.

Question 26

chemical reactions

Answer 26

involves the formation or breaking of chemical bonds, Atoms shift from one molecule to another without any change in number or identity of atoms

the extent of a chemical reaction is influence by temperature, concentration of reactants and products, catalysts

many reactions are reversible

Question 27

reactants

Answer 27

the original molecules

Question 28

products

Answer 28

the molecules resulting from the reaction

Question 29

synthesis reactions

Answer 29

smaller particles are bonded together to form more complex molecules

ex. amino acids into protein molecule

Question 30

decomposition reactions

Answer 30

bonds in larger molecules are broken, resulting in smaller less complex molecules

ex. glycogen into glucose molecules

Question 31

exchange reactions

Answer 31

bonds are both made and broken

ex. ATP transfers its terminal phosphate group to a glucose molecule to from glucose-phosphate

Question 32

cohesion

Answer 32

refers to the attraction between molecules of the same substance. It is responsible for keeping the molecules together and giving a liquid its surface tension

polarity of water allows water molecules to be attracted to one another

Question 33

adhesion

Answer 33

refers to the attraction between molecules of different substances. It is what causes a liquid to stick to a surface

water molecules stick to other polar molecule by hydrogen bonding

Question 34

acid

Answer 34

an electrolyte

have a pH range of anything below 7

proton donor

They release hydrogen ions (bare protons) when released in an aqueous solution, dissociate in water

Question 35

base

Answer 35

an electrolytes

proton acceptors

have a pH range of anything below 7

They pick up hydrogen ions in a solution, when it dissolves in a solution it releases a hydroxyl ion (OH-)

Question 36

proton donor

Answer 36

acids

Question 37

proton acceptor

Answer 37

bases

Question 38

pH scale (acid-base concentration)

Answer 38

measurement of concentration of hydrogen ions [H+] in a solution

The more hydrogen ions in a solution, the more acidic that solution is

pH is negative logarithm (so each pH unit represents a 10-fold difference) of [H+] in moles per liter that ranges from 0-14

Example: a pH 5 solution is 10 times more acidic than a pH 6 solution

Question 39

neutralization reaction

Answer 39

acids and bases are mixed together
Displacement reactions occur, forming water and a salt

Question 40

buffers

Answer 40

resist abrupt and large swings in pH
Can release hydrogen ions if pH rises
Can bind hydrogen ions if pH falls

Question 41

properties of water

Answer 41

High specific heat/heat capacity (prevents sudden temp changes)
High heat of vaporization – useful cooling mechanism for organism
Polar solvent properties – causes ionic substances to dissolve and it forms hydration layers around electrolytes
Reactivity – necessary in reaction (hydrolysis & dehydration synthesis)
Organizes nonpolar molecules – separates hydrophilic and hydrophobic molecules
Forms ions – due to breaking & deforming of the covalent bonds of H2O molecule

Question 42

Why do carbon atoms tend to make 4 covalent bonds?

Answer 42

Carbon has four valence electrons, and due to the octet rule, it needs 8 to have a full outer shell.

To achieve a stable electron configuration, carbon needs to gain or lose four electrons, which is energetically unfavorable for ionic bonding. So that is why carbon tends to favor covalent bonds, allowing it to form a variety of structures making it a central element in biological molecules.

Question 43

What determines an element’s reactivity and bonds they form?

Answer 43

valence electrons, stability of the electrons in the atoms, type of chemical bonds it can form
ELECTRONS DETERMINE

Question 44

chemical behavior of an atom

Answer 44

typically determine by electron arrangement & number of electrons