The Chemical Context of Life

Question 1

what are organisms composed of?

Answer 1

organisms are composed of matter.

Question 2

what is matter?

Answer 2

matter is anything that takes up space and has mass.

Question 3

what is matter made of?

Answer 3

matter is made of elements.

Question 4

what are elements?

Answer 4

elements are substances that cannot be broken down to other substances by chemical reactions.

Question 5

how many naturally occurring elements are there and how many elements in general?

Answer 5

there are 92 naturally occurring elements and 118 in general.

Question 6

how many of the naturally occurring elements are essential elements?

Answer 6

20-25% of the naturally occurring elements are essential elements.

Question 7

what are essential elements?

Answer 7

essential elements are hose that an organism requires in order to remain healthy and reproduce.

Question 8

what are the main 4 elements needed by the human body?

Answer 8

oxygen, carbon, hydrogen, nitrogen.

Question 9

what elements make up 96% of living matter?

Answer 9

oxygen, carbon, hydrogen, and nitrogen.

Question 10

what elements make up the remaining 4% of matter?

Answer 10

calcium, phosphorus, potassium, sulphur, sodium, chlorine, and magnesium.

Question 11

what are trace elements?

Answer 11

trace elements are only required by the organism in very small amounts.

Question 12

what are some examples of trace elements?

Answer 12

iron, iodine, copper, boron, chromium, cobalt, fluorine, manganese, selenium, tin, zinc, silicon, molybdenum.

Question 13

what are the effects of essential element deficiencies?

Answer 13

nitrogen deficiency: nitrogen is essential for plant growth and plays a crucial role in producing chlorophyll. with nitrogen deficiency it can lead to dying and yellowing of crops.
iodine deficiency: goiter (enlarged thyroid gland).

Question 14

which of the following is not a trace element in the human body? iodine, zinc, iron, calcium, fluorine?

Answer 14

calcium.

Question 15

what are elements composed of?

Answer 15

an element is composed of small units of matter that still retain the properties of an element. these small units of matter are called atoms.

Question 16

what are atoms composed of?

Answer 16

small particles called subatomic particles

Question 17

what are the 3 main subatomic particles?

Answer 17

• neutrons: no electrical charge
• protons: positively charged
• electrons: negatively charged

Question 18

where are protons and neutrons found?

Answer 18

protons and neutrons are found in the nucleus of an atom.

Question 19

where are electrons found?

Answer 19

electrons surround the nucleus in a cloud.

Question 20

the number of electrons an element has can be identified by?

Answer 20

its atomic number.

Question 21

the number of protons an element has can be identified by?

Answer 21

its atomic number.

Question 22

how to find the number of neutrons an atom has?

Answer 22

the number of neutrons = mass number - atomic number

Question 23

what is a compound?

Answer 23

a compound is a substance consisting of two or more elements combined in a fixed ratio. it has characteristics different from those of its elements.

Question 24

are the electrons of an atom found at the same distance from the nucleus?

Answer 24

no, the electrons are found at varying distances away from the nucleus of an atom. they vary in the amount of energy they possess. the electrons that are further away, have more energy.

Question 25

what is the chemical behavior of an atom defined by?

Answer 25

the chemical behavior of an atom is defined by its electron configuration and distribution.

Question 26

how do you determine how many electron shells an element has?

Answer 26

depends on the number of electrons (the atomic number). the first shell has 2 electrons, second shell has 8, third shell has 8.

Question 27

what would the electron shells of a sodium atom look like if the atomic number is 11.

Answer 27

it would have 3 shells. 2 atoms in the first one, 8 in the second shell, and 1 in the third shell.

Question 28

what are valence electrons?

Answer 28

valence electrons are the electrons in the outermost electron shell.

Question 29

what in specific determines the chemical behavior of an atom?

Answer 29

the valence electrons.

Question 30

what is the valence shell?

Answer 30

the outermost shell is called the valence shell.

Question 31

what is the valence of an atom?

Answer 31

the valence of an atom is the number of unpaired electrons in its valence shell.

Question 32

how many valence electrons does na have? what is the valence of na?

Answer 32

1, 1

Question 33

if the valence shell is full…?

Answer 33

if the valence shell is filed to capacity, the atom is inert/unreactive

Question 34

if the valence shell isn’t full…?

Answer 34

if the valence shell is not full, it is reactive. it can combine and interact with other atoms it comes into contact with.