Atoms and Elements

Question 1

Elements

Answer 1

pure substances from which all other things are built. they cannot be broken down into simpler substances

Question 2

heterogeneous mixture

Answer 2

made up of distinct regions because the atoms or molecules that compose them separate

Question 3

homogeneous mixture

Answer 3

has uniform compositions because the atoms or molecules that compose them are uniform

Question 4

Mercury

Answer 4

• forms amalgams with other elements including gold, and aluminum [not allowed on aircraft]

Question 5

how can mercury enter the body?

Answer 5

by mercury vapor inhalation, contact with the skin, ingestion of food or water contaminated with mercury

Question 6

what is the effect of long-term exposure of mercury?

Answer 6

damage the brain and kidneys
mental retardation
decrease physical development

Question 7

mad hatter disease

Answer 7

treatment of animal furs with mercury nitrate for felting. there were no safety measures. as a result, exposure lead to neurological symptoms: tremors and irritability

Question 8

give examples of metalloids

Answer 8

boron, silicon, germanium, arsenic

Question 9

periodic law

Answer 9

when the elements are arranged in order of increasing mass certain sets of properties recur periodically

Question 10

group 1A

Answer 10

Alkali metals

-shiny, good conductors of electricity
- low melting points
- react vigorously with water
- form monovalent cations

Question 11

group 2A

Answer 11

alkaline earth metals

form stable divalent cations

Question 12

group 7A

Answer 12

Halogens

form stable monovalent anions

Question 13

describe metalloids

Answer 13

classified as semiconductors because of their intermediate electrical conductivity.

Question 14

examples of macrominerals

Answer 14

calcium, phosphorus, potassium, sulfur, sodium, and magnesium

Question 15

what does it mean if the solid matter may be crystalline?

Answer 15

its atoms or molecules are in patterns with long-range repeating order

Question 16

what does it mean if the solid matter may be amorphous?

Answer 16

its atoms and molecules do not have long-range order

Question 17

decanting

Answer 17

carefully pouring off

Question 18

distillation

Answer 18

separate a homogeneous mixture of liquids: the volatile liquid will be heated to boil off first and then recondensed a condenser and collected in a separate flask

Question 19

filtration

Answer 19

if a mixture is composed of an insoluble solid and liquid

Question 20

law of conservation of energy

Answer 20

energy is neither created nor destroyed

Question 21

chemical potential energy

Answer 21

the energy contained in the molecules

Question 22

extensive property

Answer 22

depends on the amount of the substance

Question 23

measure of time

Answer 23

seconds

Question 24

how are seconds defined?

Answer 24

the duration of 9,200,000,000 periods of the radiation emitted from a certain transition in a cesium 133 atom

Question 25

converting kelvin to Celcius

Answer 25

K= C + 273.15

Question 26

intensive property

Answer 26

one that is dependent on the amount of the substance ie. density

Question 27

four elements that makeup 96% of our body mass

Answer 27

oxygen

carbon

hydrogen

nitrogen

Question 28

describe osteoporosis

Answer 28

young adults have a bone density of about 1.0g/cm3 whereas individuals with osteoporosis have bone densities as low as 0.22g/cm3. low-density bones absorb less of the X-rays than do high-density bones, producing characteristic differences in the X-ray image

Question 29

accuracy

Answer 29

how close the measured value is to the actual value

Question 30

precision

Answer 30

refers to have close a series of measurements are to one another or how reproducible they are

Question 31

random error

Answer 31

results that are both inaccurate and imprecise: can average itself out with enough trials

Question 32

systematic error

Answer 32

results that are precise but inaccurate: does not average itself out with repeated trials