Lecture 2: Chemistry and Water

Question 1

what is matter

Answer 1

anything that takes up space and has mass

Question 2

what is an atom

Answer 2

the smallest functional units of matter

Question 3

what are elemnts

Answer 3

substances that cannot be broken down into other substances

Question 4

What element makes up our macromolecules

Answer 4

Carbon

Question 5

protons

Answer 5

positive charge

Question 6

neutrons

Answer 6

neutral charge

Question 7

electrons

Answer 7

negative charge

Question 8

where are protons and neutrons located in the atom

Answer 8

they are clustered around the center of the atom

Question 9

where are electrons located in the atom

Answer 9

they are in a fixed distance and move in an orbit around the nucleus

Question 10

how many electrons are in the first orbit surrounding the nucleus?

Answer 10

at most up to two electrons

Question 11

how many electrons are found in the second shell orbiting the nucleus?

Answer 11

second shell will hold 8 electrons

Question 12

when are atoms most stable?

Answer 12

when their outermost shell is built with 8 electrons

Question 13

what happens when atoms are less stable

Answer 13

they lose some of their different particles which cause radiation; but they can share electrons and form bonds to become more stable

Question 14

what is an ion

Answer 14

element that has a different number of electrons

Question 15

Anion

Answer 15

ion with an extra electron (H^-1)

Question 16

Cation

Answer 16

ion missing an electron (H^+1)

Question 17

Can electrons grab onto free energy

Answer 17

yes

Question 18

free radicals

Answer 18

formed by electrons; when an atom or molecule has a single, unpaired electron in its outer shell; can harm a cell’s DNA and essential functions;
can be caused by cigs and UV rays; antioxidants help

Question 19

atomic number

Answer 19

how many protons it has

Question 20

mass number

Answer 20

weight; determined by the number of protons and neutrons (electrons have no weight)

Question 21

isotopes

Answer 21

atoms of an element that have a different number of neutrons than protons (hydrogen)

Question 22

radioisotopes

Answer 22

unstable and emit particles and energy in order to stabilize themselves; odd number of neutrons;
their radiation can be used for X-rays and treatment for cancer

Question 23

why are electrons important

Answer 23

1) can form bonds and are then stuck together
2) determine if the atom is an ion
3) capture and transfer energy
4) form destructive free radicals

Question 24

molecule

Answer 24

two or more atoms linked by bonds

Question 25

covalent bond

Answer 25

2 atoms share a pair of electrons

relatively stable but are THE MOST STABLE IN AQUEOUS ENVIRONMENTS

H2O IS A COVALENT BOND

Question 26

Electronegativity

Answer 26

in some bonds, the electrons are shared closer to one nucleus than the other

ex: in water, oxygen molecule is more electronegative (pulls the electrons closer) than the hydrogen atoms

Question 27

Polar covalent bond

Answer 27

one side is more positive and one side is more negative

ex: in water molecules, electrons are held unevenly;
ex: O-H and N-H

Question 28

nonpolar covalent bond

Answer 28

two atoms have an equal electronegativity, meaning the electrons are shared equally

ex: C-C and C-H

Question 29

polar molecules

Answer 29

have a positive charge on one end and a negative charge on the other

Question 30

nonpolar molecule

Answer 30

when a molecule is composed of nonpolar covalent bonds and the entire molecule has the same charge all over

Question 31

ionic bonds

Answer 31

form when oppositely charged atoms are attracted to one another

very stable in atmospheric or air environments

in a watery environment, the bond will fall apart or dissociate

Question 32

Hydrogen bonds

Answer 32

weak bonds

end of a polar molecule attracts the other end of a polar molecule

gives water the property of surface tension

gives the 3-D shape of molecules

DNA sides are held together by hydrogen bonds

proteins are held together by hydrogen bonds

Question 33

conformational change

Answer 33

change in shape of the molecule and it occurs when two molecules come close together bc

1) new covalent bonds cause electron reorganization
2) new molecule exerts weak electrochemical forces

Question 34

Chemical reactions are

Answer 34

reversible

Question 35

a chemical reaction has ________ and ________

Answer 35

reactants (starting molecules) and products (resulting molecules)

Question 36

what is the direction of the chemical reaction determined by?

Answer 36

it is determined by the concentration of the reactants and products, and often will continue to equilibrium

Question 37

water

Answer 37

polar molecule

makes hydrogen bonds with other polar molecules

hydrophilic

universal solvent

moderates temp

cohesive

solute

Question 38

what 3 states does water exist in?

Answer 38

ice: h bonds are more stable; form a hexagonal crystal

liquid water: h bonds at 180; water molecules compressed and have higher density

gas (steam): H bonds are broken; water molecules travel individually

Question 39

hydrolysis reaction

Answer 39

molecule will be split into two in the presence of water

Question 40

condensation reaction

Answer 40

molecule of water is taken as two molecules bind together

Question 41

Bases

Answer 41

ph higher than 7 (fewer H+ ions)

any substance that dissociates into one or more hydroxyl ions and one or more positive ions

ex: NaOH–> Na+ and OH-

Question 42

acids

Answer 42

ph lower than 7 (more H+ ions)

anything that dissociates into one or more H+ ions and one or more negative ions

ex: HCl–> H+ and Cl-

Question 43

Buffer

Answer 43

a substance that moderates changes in pH

have negative ions that attract H+ or a weak acid that combines with a base to make water