Ch. 2 The Chemical Basis of Life Mrs. Dugas

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define atomic number

# of protons

what does each element differ in

# of protons, neutrons, & electrons

how much iodine do you need a day & where do people put iodine so we can get enough each day

.15 mg, put in salt

what elements does DNA contain (5)

1. cardon, 2. hydrogen, 3. oxygen, 4. nitrogen, & 5. phosphorus

why are chemicals added to food (3)

1. help preserve it, 2. make it more nutritious, & 3. makes it look better

what elements are our body mostly made of (4)

1. oxygen, 2. carbon, 3. hydrogen, & 4. nitrogen

what are some dangers associated with using radioactive substances (2)

1. uncontrolled exposure can cause damage to molecules in living cells & DNA, & 2. chemical bonds are broken by the emitted energy which causes abnormal bonds to form

how many shells can an atom have & how many electrons can fit in each

1st shell- 2 electrons, 2nd shell- 8 electrons, 3rd shell- 8 electrons

how many elements does life require

25

define trace elements

25 essential elements that are required for life & needed in minute quantities

how many elements are there in nature & what kind of state do only a few of them exist in

92 elements, in a pure state

what is a showcase of the diversity of life on Earth

Amazon rain forest

what is matter composed of

chemical elements

what is at the base level of biological hierarchy

chemicals

what makes up our bodies, other organisms, & the physical environment

chemicals

what does Fluorine do for your body

cleans your teeth

what do atoms in a covalent bond do

continually compete for shared electrons

what is the PET useful for

diagnosing heart disorders & cancer & in brain research

define electron shells

energy levels where electrons are located

define nonpolar covalent bonds

equal sharing, pull of each atom is equal & atom is neutral

what do the arrangements of biological hierarchy usually lead to

formation of living organisms

define molecule

formed when atoms are held together by covalent bonds

where is information about the distribution of electrons found

in the periodic table of elements

how can radioactivity be detected

instruments

what kind of ions attract together

ions with opposite charges

define neutrons & where is it found

is electrically neutral, in nucleus

what can living cells not distinguish between

isotopes of same element

what does a neutron do in an atom

makes atom heavier but doesnt change charge

what does the structural formula show

map of atoms

what are living things composed of

matter

what are radioactive tracers frequently used in

medical diagnosis

define polar molecules

molecules with unequal distribution of charges

does a covalent bond have a charge

no because shared electrons don't change charges

are hydrogen bonds strong

no they are weak

what cant polar dissolve

nonpolar

what determines the chemical properties of the atom

number of electrons in outtermost shell

define hydrogen bond

one attracts to next

what is involved in chemical activity

only electrons

what are water molecules electrically attracted to

oppositely charged regions on neighboring molecules

what does a polar molecule attract

other polar & ionic

what are atoms made of & how many are important for biological compounds

over a hundred subatomic particles, only 3 are important

what does an iodide deficiency prevent

production of thyroid hormones, resulting in Goiter

what do more electronegative atoms do

pull harder

what happens to the pull of molecules of only one element & why does this happen

pull toward each atom is equal because each atom has the same electronegativity

what does hydrogen as part of a polar covalent bond do

share attractions with other electronegative atoms

when you share electrons they are, when you give electrons they are

share electrons- molecules, give electrons- ions

what does the molecular formula show

shows what atoms & how many

define electron & where is it found

single negative charge electrical charge, in electron cloud

define proton & where is it found

single positive electrical charge, in nucleus

define atom

smallest unit of matter that still has properties of an element

what is an example of a compound

sodium & chlorine

define compound

substance consisting of 2 or more different elements combined in a fixed ratio

how do you get the # of neutrons

subtract mass number to the atomic number

define mass number

sum of protons & neutrons in nucleus

what does a positron-emission tomography (PET) detect

the location of injected radioactive materials

what does the ordering of atoms into molecules represent

the lowest level of biological organization

what keeps electrons near the nucleus

the negative charge of electrons & positive charge of protons

what do radioactive compounds used in metabolic processes act as

tracers

what does iron do in your body

transport oxygen

what is important to understand in order to understand life

understand the basic concepts of chemistry

define polar covalent bond

unequal sharing, electrons spend more time near the stronger pulling atom

define isotopes

variations that have same number of protons & electrons but different number of neutrons

define covalent bond

when atoms share outershell electrons

define ionic bond

when attraction holds ions together, donate & receive

what happens when an electron is lost, & when one is gained

when lost- a positive charge occurs, when gained- a negative charge occurs

does an ionic bond have a charge

yes

does oxygen attract shared electrons more strongly than hydrogen

yes

what is polar like

a magnet

define elements

a substance that cannot be broken down to other substances

define matter

anything that occupies space & has mass (weight)

define ion

atom or molecule with an electrical charge reulting from gain or loss of electrons

define octet rule

atoms wanting to fill their outermost electron shell until it is full

what kind of atoms does water have

atoms with different electronegativities

define electronegativity

attraction (pull) for shared electrons

define chemical bond

attraction between atoms

what are some examples of trace elements

boron, chromium, copper, cobalt, & fluorine

how do atoms accomplish filling their outermost electron shell

by sharing, donating, or receiving electrons


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