chemical bonds and molecules

Question 1

what is a molecule

Answer 1

2 or more atoms held together by chemical bonds

Question 2

what is a compound

Answer 2

any molecule composed of 2 or more elements

Question 3

what is a molecular formula

Answer 3

chemical symbols of the elements in the molecule with the number of each shown (C6H12O6)

Question 4

what are covalent bonds

Answer 4

when electrons are shared to fill valance shells

Question 5

what are the 2 types of covalent bonds

Answer 5

1. polar covalent
2. non-polar covalent

Question 6

what are hydrogen bonds

Answer 6

when a hydrogen atom from one polar molecule is attracted to an electronegative atom from another molecule

Question 7

what are ionic bonds

Answer 7

when electrons are transferred, forming ions that are attracted to each other

Question 8

are covalent bonds strong or weak? stable or not?

Answer 8

strong and energetically stable

Question 9

when are atoms stable (in a low energy state)

Answer 9

when their outer shell s and p electrons are full

Question 10

what is electronegativity

Answer 10

a measure of an atoms ability to attract shared electrons towards its own positive charge

Question 11

what do differences in electronegativity dictate

Answer 11

how electrons are distributed in covalent bonds

Question 12

what are non-polar covalent bonds

Answer 12

when there is an equal sharing of electrons (balanced)

Question 13

what are polar covalent bonds

Answer 13

when there is an unequal sharing of electrons (partial positive on one side, partial negative on the other). atoms of different electronegativity

Question 14

in polar covalent bonds, what element do the atoms tend to be closer to

Answer 14

the more electronegative element

Question 15

what are nonpolar covalent bonds

Answer 15

bonds between atoms with similar electronegativities. there is an equal sharing of electrons and no charge difference across the molecule

Question 16

how are hydrogen bonds drawn

Answer 16

as a dotted line

Question 17

are hydrogen bonds strong or weak

Answer 17

weak electrostatic bonds

Question 18

what are hydrogen bonds made of

Answer 18

hydrogens with a partial positive charge and other atoms with a partial negative charge (typically oxygen and nitrogen)

Question 19

what connection do hydrogen bonds have to water

Answer 19

• water molecules interact with one another via hydrogen bonds
• hydrogens with partial positive charges are attracted to oxygens with partial negative charges
• responsible for many of water’s important physical properties

Question 20

how are hydrogen bonds related to DNA and proteins

Answer 20

they are largely responsible for the structure of DNA and proteins as well as interactions between these macromolecules

Question 21

how are hydrogen bonds responsible for the structure of DNA and proteins

Answer 21

you can seperate DNA because hydrogen bonds are so weak

Question 22

what is an ion

Answer 22

an atom or molecule that has gained or lost one or more electrons so the net charge is not neutral

Question 23

what charge do cations have

Answer 23

a net positive charge

Question 24

what charge do anions have

Answer 24

a net negative charge

Question 25

what is an ionic bond

Answer 25

when a cation binds to an anion by electrostatic (charge) attraction

Question 26

what are the 2 types of ions

Answer 26

1. cations
2. anions

Question 27

what are ionic compounds

Answer 27

salts

Question 28

what is a chemical reaction

Answer 28

when one or more substances are changed into other substances

Question 29

what is the equation of a chemical reaction

Answer 29

reactants -> products

Question 30

many chemical reactions often require what?

Answer 30

a source of energy

Question 31

in order to make chemical reactions, what energy source is often used for living organisms

Answer 31

an enzyme as catalyst

Question 32

where do chemical reactions most often occur

Answer 32

in liquid (in life- water)