chapter two

Question 1

matter

Answer 1

anything that has mass and takes up space

Question 2

element

Answer 2

a substance that cannot be broken down into another substance by chemical reactions

Question 3

atoms

Answer 3

smallest units of elements
- not tiniest particle

Question 4

molecule

Answer 4

2+ atoms held together by chemical bonds (usually covalent)

Question 5

compound

Answer 5

2+ different atoms held together by chemical bonds in a fixed ratio
- compounds are molecules

Question 6

how many elements are essential for life?

Answer 6

• 20-25% of 92 natural elements
• 25 elements for humans

Question 7

96% of living material is composed of what elements?

Answer 7

carbon, nitrogen, oxygen, hydrogen

Question 8

trace elements

Answer 8

elements that are required by an organism in minute quantities
- ex. iron, iodine, manganese

Question 9

3 subatomic particles

Answer 9

proton, neutron, electron

Question 10

atomic number

Answer 10

number of protons

Question 11

mass number

Answer 11

protons + neutrons

Question 12

atomic mass

Answer 12

unrounded neutrons, protons, electrons
- average for all natural isotopes of element

Question 13

isotope

Answer 13

same number of protons, different number of neutrons

Question 14

radioactive isotope

Answer 14

isotope where nucleus decays spontaneously and emits energy and particles

Question 15

useful application of radioactive isotope

Answer 15

PET scans detects location of intense chemical activity

Question 16

energy

Answer 16

the ability to do work

Question 17

potential energy

Answer 17

energy that matter possesses because of its location and structure

Question 18

valence shell

Answer 18

outermost electron shell

Question 19

electron orbitals

Answer 19

3d space where electron found 90% of time

Question 20

chemical bonds

Answer 20

attractions that keep atoms together

Question 21

electronegativity

Answer 21

the attraction of an atom for an electron of a covalent bond

Question 22

periodic table atoms on the left

Answer 22

have lower electronegativity
- lose e, become cation
- Na, Mg

Question 23

periodic table atoms on the right

Answer 23

have higher electronegativity
- gain e, become anion
- Cl, F

Question 24

covalent bond

Answer 24

sharing of electrons

Question 25

single bond

Answer 25

1 pair of electrons shared

Question 26

double bond

Answer 26

2 pairs of electrons shared

Question 27

ex of structural formula

Answer 27

H-H

Question 28

ex of molecular formula

Answer 28

H(2), C(6)H(12)O(11)

Question 29

valence

Answer 29

bonding capacity - number of electrons required to complete valence shell

Question 30

nonpolar covalent bond

Answer 30

- true covalent bond - equal sharing of electrons - H-Hp

Question 31

when is outer shell full?

Answer 31

8 electrons

Question 32

when is innermost shell full?

Answer 32

2 electrons

Question 33

where are polar covalent bonds in relation to water molecules?

Answer 33

within

Question 34

polar covalent bond

Answer 34

electrons not shared equally

Question 35

ionic bond

Answer 35

electrons transferred between atoms - cations/anions formed

Question 36

where do ionic bonds happen?

Answer 36

between elements that have unequal attractions for valence electrons

Question 37

ion

Answer 37

charged atom as result of ionic bond

Question 38

cation

Answer 38

positively charged ion

Question 39

anion

Answer 39

negatively charged ion

Question 40

ionic compounds/salts

Answer 40

compounds formed by ionic bonds - NaCl sodium chloride - MgCl(2) magnesium chloride

Question 41

hydrogen bond

Answer 41

weak bond between hydrogen (covalently bonded to EN atom) and another EN atom (of 2nd molecule, usually O/N)

Question 42

Vand der Waals interactions

Answer 42

ever-changing regions of +/- charge enable atoms and molecules to stick together - only when close

Question 43

strength of bonds from strongest to weakest

Answer 43

covalent, ionic, hydrogen, van der waals

Question 44

function of the molecule is related to what?

Answer 44

shape or size

Question 45

chemical reactions

Answer 45

making and breaking bonds that leads to a change in composition of matter

Question 46

reactant

Answer 46

starting materials

Question 47

product

Answer 47

ending molecules