Chapter 2

Question 1

matter

Answer 1

anything that takes up space and has mass

Ex: rocks, oils, gases

Question 2

element

Answer 2

substance that cannot be broken down into other substances by chemical reaction
o 92 elements

Question 3

compound

Answer 3

substance consisting of two or more elements combined in a fixed ratio
Ex: Emergent properties: Compound has different properties than element.

Question 4

Essential elements

Answer 4

20-25% of the natural elements an organism needs to live a healthy life and reproduce (~25 elements)
o O, C, H, N (make 96% living matter) Ca, P, K, S

Question 5

Trace elements

Answer 5

required by organism in small quantities only

o Ex: Fe, I (vertebrates)

Question 6

Atom

Answer 6

the smallest unit of matter that still retains the properties of an element
o	Subatomic particles
•	Neutrons
•	Protons: no of protons identifies atom
•	Electrons

Question 7

mass number

Answer 7

sum of p+n

Question 8

atomic number

Answer 8

number of protons

Question 9

Isotopes

Answer 9

different atomic forms of the same element

o Same amount of protons, different amount of NEUTRONS

Question 10

Radioactive isotope

Answer 10

nucleus decays spontaneously, giving off particles and energy

Question 11

half life

Answer 11

amount it takes for ½ of parent isotope to decay into daughter isotope

Question 12

radiometric dating

Answer 12

process through which scientists measure the ratio of different isotopes to calculate how many half lives (in years) have passed since organism has fossilized

Question 13

energy

Answer 13

the capacity to cause change, for instance, by doing work

Question 14

electron shells

Answer 14

have characteristic distance and energy level

o Represents average distance between electron and the nucleus

Question 15

valence shell

Answer 15

outermost shell of electrons

Question 16

orbital

Answer 16

the 3D space where an electron is found 90% of the time

Question 17

electronegativity

Answer 17

the attraction of a particular atom for the electrons of a covalent bond

Question 18

ions

Answer 18

two oppositely charged atoms

Question 19

ionic bond

Answer 19

transfer of electrons, significant electronegativity difference

Question 20

ionic compounds/salts

Answer 20

compounds formed by ionic bonds

o Consist of lattice anions and cations

Question 21

Hydrogen bond

Answer 21

attraction between H and electronegative atom (usually O or N)

Question 22

Van der Waals forces

Answer 22

charge is not always evenly distributed. Positive and negative regions change.
Ex: these allow a gecko to walk up a wall

Question 23

Law of Conservation of Atoms

Answer 23

Atoms are neither created or destroyed, but rearranged.

Question 24

chemical equilibrium

Answer 24

forward and reverse reactions occur at same rate and offset each other.
o Dynamic
o There is not net effect on concentrations of reactants or products.
o Reacts & products are NOT at equal concentrations but have stabilized at a particular ratio.