quizlet ch 2-5

matter

anything that has mass and occupies space

an element is made up of

1 type of atom

there are how many natural elements

92

each element has a

symbol

life requires how many chemical elements

25

how many make up 96% of all living matter; tell which ones

carbon, oxygen, hydrogen, and nitrogen

compound

elements combined in fixed ratios (ex. H2O= 2 H 1 O

a compound had characteristics beyond those of its

combined elements

macroelements

elements needed in large amounts or quantities

what are examples of macroelements

Calcium, hydrogen, oxygen, phosphorus, sulfur, magnesium, and sodium chloride

microelements

elements needed in very small quantities

microelements are also known as

trace elements

what are examples of microelements

copper, cobalt, zinc, milidium, iodine, and manganese

atoms

the smallest particles of elements that are made up of protons (+), neutrons (0), and electrons (-)

atomic number

the number of protons in the nucleus

each element has its own

atomic number and if you change the atomic number, you no longer will have the same element

atomic mass

the number of protons and neutrons in the nucleus

the atomic mass can

change

isotopes

atoms of the same (iso-) element with different atomic mass

isotopes are caused by changes in

number of neutrons

isotopes are used as

tracers

what are the 2 types of isotopes

radioactive and heavy

radioactive isotopes are where

the nucleus decays spontaneously, giving off particles and energy

heavy isotopes have

a stable nucleus, but masses more than the standard isotope for the element

energy

the ability to do work

potential energy

energy that matter stores because of its position/location

electrons have potential energy because

of their position relative to the nucleus

electron energy levels

energy levels around the nucleus of an atom

the 1st level can have

2 electrons and has the lowest potential energy

other levels can hold

more than 2 electrons and have higher energy levels

electron orbitals

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

different orbitals have

different shapes

each orbital can hold

only 2 electrons

the chemical behavior of an atom is determined by

its electron configuration in the energy levels and orbitals

valence electrons

the electrons in the outermost energy level

valence electrons are available to

form chemical bonds

in the octet rule, the most stable condition is

to have an outer level of 8 electrons

the exception of the octet rule is that the

first level is stable with only 2 electrons

when stable in the octet, there is

no chemical reactions that take place

2 examples of that are

neon and helium

chemical bonds

forces that join atoms together to form molecules

chemical bonds are usually caused by

sharing or transferring valence electrons

bond formation depends on

the number of valence electrons that must be gained, lost, or shared to reach the stable condition

what are the 4 chemical bond types

nonpolar covalent, polar covalent, ionic, and hydrogen

nonpolar covalent bond

bond that forms with 2 bonds that share equally

polar covalent bond

don't share equally because 1 atom will be more electronegative

ionic bond

will either donate or accept an electron

hydrogen bond

attracted force between partial bond

nonpolar covalent bonds are important in

many molecules found in living things

2 examples of a nonpolar covalent bond is

carbon and hydrogen

nonpolar covalent bonds can be

single, double, or triple bonds between 2 atoms

each nonpolar covalent bond

involves a pair of electrons

polar covalent bonds result in

polar molecules that have charged areas

what is an example of a polar covalent bond

water, hydrogen to oxygen bonds

what are 2 types of ions

cations and anions

cations have

lost electrons giving them a positive charge

anions have

gained electrons giving them a negative charge

ioinic bonds are formed when

cations and anions attract eachother

compounds formed from ionic bonds are called

salts

when a hydrogen atom bonded to one molecule is

attracted to a slightly negative area (often Nitrogen or Oxygen) of another molecule

how strong/weak is a hydrogen bond

very weak individual bond, but can be a strong force if there are many hydrogen bonds

list the types of bonds from strongest to weakest

nonpolar, polar, ionic, hydrogen

the molecular shape is determined by the

positions of the atom's orbitals

molecular 3-dimentional shape is important in biology because it determines

how most molecules of life recognize and respond to one another

chemical reactions

the making and breaking of chemical bonds

reactions do not destroy matter,

they only rearrange it

reactants

the starting materials

products

the ending materials

all atoms of the reactants must be

accounted for in the products

chemical equilibrium

when the conversion of the reactants to products is balanced to the reverse reaction

when you see a double arrow,

reactants are balanced to the reverse

water is

the most common molecule in living cells

most cells are

70%-95% water

what are the 6 properties of water

cohesion, adhesion, high surface tension, high specific heat, high heat of vaporization, and it expands when it freezes

cohesion

water sticks to water

why is water cohesive

water is a polar molecule that has a positive charge on the hydrogen and partial charge on the oxygen; these partial charges attract and form hydrogen bonds with other molecules helping them stick together

adhesion

water sticks to other molecules

why is water adhesive

because of the polarity of water molecules, hydrogen bonding occurs between water and other electronegative molecules, causing them to stick together

*polar means that it has

charges and likes to stick to other polar molecules

water transport in trees uses

cohesion and adhesion

the surface tension of water is

difficult to stretch or break

why does water have a high surface tension

cohesion between water molecules (hydrogen bonding)

specific heat

the amount of heat needed to raise 1 gram of the substance 1 degree Celsius

why does water have a high specific heat

water has to absorb a ton of energy to overcome cohesive forces in hydrogen bonding and increase molecular movement

heat

the total quantity of kinetic energy due to molecular motion

heat depends on the

volume of molecules

heat is measured in

calories

if you break a bond, absorb energy, then the

hydrogen bonds will move faster

temperature

measures the average speed of the molecules

temperature doesn't depend on

volume

water stabilizes temperature because of its

high specific heat

water can absorb and store a huge amount of

heat energy from the sun without changing its own temperature much

the result of water absorbing and storing is that

organisms are able to survive external temperature changes and maintain homeostasis

heat of vaporization

the quantity of heat energy a liquid must absorb for 1 gram of it to convert to a gaseous state

why does heat of vaporization occur

becuase liquid water has to absorb a lot of energy to overcome cohesive forces in hydrogen bonding and increase molecular movement to the point where it can evaporate

when vaporization occurs,

it causes evaporative cooling-- where molecules will vaporize and take sweat= causing cooling

when water expands when frozen, the distance between water molecules

increases and becomes less dense from the liquid to the solid form.

why does water expand when it freeezes

becaue of hydrogen bonding-cool temperatures make hydrogen bonds stop breaking and reforming, locking them into a lattice structure that is spread out, this makes the volume larger and less dense in solid form

because ice floats and acts as an insulator,

aquatic life can live under ice

water is a versatile solvent (just a characteristic--not exactly a property)

water will form a solution with many materials