Chapter 1

Question 1

what are organisms composed of?

Answer 1

matter

Question 2

what is matter?

Answer 2

matter is anything that occupies space/volume and has mass

Question 3

what is matter made up of? and what are they?

Answer 3

elements; substances that cannot be broken down into simpler substances by chemical reactions

Question 4

how many naturally occurring elements are there? how many elements are there at all?

Answer 4

there are 92 naturally occurring elements but 118 in the periodic table

Question 5

what is an essential element and what % of the elements are considered essential elements?

Answer 5

essential elements are those that an organism requires in order to remain healthy and reproduce.
20-25% of the elements in the periodic table are considered essential elements

Question 6

what are the 4 main elements in the human body?

Answer 6

oxygen, carbon, hydrogen, and nitrogen

Question 7

what elements make up 96% of living matter?

Answer 7

oxygen, carbon, hydrogen, and nitrogen

Question 8

what are trace elements and some examples?

Answer 8

trace elements are the elements that are only required by the organism in very small amounts.
iron and iodine

Question 9

what elements make up the other 4%?

Answer 9

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

Question 10

what is the effect of iodine deficiency?

Answer 10

goiter: enlarged thyroid gland

Question 11

what is the effect of nitrogen deficiency?

Answer 11

reduced crop yields, low quality produce, reduced soil fertility

Question 12

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

Answer 12

calcium

Question 13

what is an element composed of?

Answer 13

elements are composed of building blocks called atoms.

Question 14

atoms are composed of?

Answer 14

smaller parts called subatomic particles.

Question 15

what are the subatomic particles of an atom?

Answer 15

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

Question 16

where are protons and neutrons found?

Answer 16

atomic nucleus

Question 17

where are electrons found?

Answer 17

surround the nucleus in shells

Question 18

what is the atomic number determined by?

Answer 18

the number of electrons an element has determines its atomic number.

Question 19

what is a compound?

Answer 19

a compound is a substance consisting of two or more elements joined by chemical bond: has characteristics different from those of its elements individually

Question 20

are electrons found at similar distances away from a nucleus?

Answer 20

no, electrons are found at different distances away from the nucleus of an atom.

Question 21

explain a bit about electron shells.

Answer 21

so first is the nucleus and then there is the first shell(2 electrons) then second shell(8 electrons) and then third shell(8 electrons).

Question 22

which electrons have more energy?

Answer 22

the electrons that are further away from the nucleus have more energy.

Question 23

which shell do electrons fill up first?

Answer 23

the lowest energy levels first: first shell

Question 24

what are valence electrons/shell?

Answer 24

the electrons in the outermost shell are called valence electrons. the outermost shell is called the valence shell

Question 25

what do valence electrons do?

Answer 25

determine the chemical behavior of an atom

Question 26

what is the valence of an atom?

Answer 26

the number of unpaired electrons in its valence shell

Question 27

how many valence electrons does Na have and what is the valence of Na?

Answer 27

1 valence electron and 1 valence

Question 28

what does it mean if the valence shell is filled to its capacity?

Answer 28

the atom is inert/unreactive

Question 29

what does it mean if the valence shell is not completed?

Answer 29

the atom is reactive and it can combine/interact with other atoms