AP BIO QUIZ - Water +Elements of Life

What causes polarity in water?

The oxygen atom is more electronegative than the two hydrogen atoms. Causing there to be a polar bound between the oxygen atom and the two hydrogen atoms

How does the addition of soap affect the surface tension of water?

The surface tension of water decreased when soap was added. Soap decreases cohesive forces

How do water molecules on the surface of water differ from the water molecules in the middle layer?

The H20 molecules on the top layer only form hydrogen bonds with molecules below it and to the side, this causes the top layer of H20 to be pulled down. This ultimately allows for the flow of H20 and nutrients against gravity

What does water in enclosed bodies of water have?

surface tension that is caused by hydrogen bonds

Why are cohesion, adhesion, and surface tension properties important to nature?

Because without these properties water wouldn’t be able to go against gravity. Without this ability water wouldn’t be able to sustain and feed the many living organisms that it supports

What is matter?

anything that takes up space and has mass

What is an element?

A substance that cannot be broken down into other substances by chemical reactions

Compound

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

What are the essential elements?

CHOPN

What are trace elements?

92 naturally occurring elements, these are required by an organism in very small qualities

What does the atomic number tell you?

number of protons

What is the atomic mass?

number of protons plus the number of neutrons, averaged over all isotopes

Elements in the same “group” have the….

same number of valence electrons

Elements in the same “period’’ have the….

same total number of electron shells

Name types of families

noble gases, alkaline, Alkaline earth, Halogens

Alkaline metals vs. Halogens

both are volatile because alkaline need to get rid of one valence electron and halogens need one more valence electron

Lewis dot Model vs. Bohr Model

lewis only shows valence electrons, Bohr shows all electrons

What is a Bohr model?

model that shows electrons orbiting the nucleus of an atom

How many electrons can be in a three shell atom? What are the different energy levels

(1st shell) 2 electrons, (2nd shell) 8 electrons, (3rd shell) 18 electrons

Lewis dot model

simplified Bohr diagrams

What is the octet rule?

elements will gain, lose, or share electrons to complete their valence shell and become stable (like noble gases)

How do elements become stable?

by forming chemical bonds with other elements

What are chemical bonds?

an attraction between 2 atoms, resulting from the sharing or transferring of valence electrons

Electronegativity

the measure of an atom’s ability to attract electrons to itself

What is a covalent bond?

when two or more atoms share electrons (usually between two non-metals)

Can covalent bonds have single, double, and triple bonds?

Yes

What are the two types of covalent bonds?

non-polar covalent and polar covalent

Non-polar covalent bond

equal sharing of electrons between two atoms

Polar covalent

electrons are not shared equally between two atoms

What is an example of a covalent bond?

H20 (oxygen is more electronegative than the two hydrogen atoms causing there to be partial negative and positive charges)

What are ionic bonds

the attraction between oppositely charged atoms, which are ions. (usually between a metal and a non-metal)

What is a cation?

positively charged ion

What is an anion?

negatively charged ion

What are hydrogen bonds?

the partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molecule

What are intermolecular bonds?

bond that forms between molecules

Considering the periodic table, what is the spectrum of electronegativity?

The further right you go the more electronegative the elements get, the further down you go the less electronegative the elements get

How do hydrogen bonds form?

The partially positive hydrogens are attracted to the negative oxygen atom of another water molecule. Water molecules are polar covalent

Why are hydrogen bonds important to water?

Makes water more structured/organized than most liquids. This in turn gives water the ability to build up surface tension, which then allows small creatures to walk on the surface of water.

• without hydrogen bonds life on earth would not exist, water is essential to life!

What is polarity

unequal sharing of electrons

what is cohesion?

attraction of molecules for other molecules of the same kind

How does cohesion happen in terms of water?

Water molecules connect to each other via hydrogen bonding

Why is cohesion important?

allows for the transport of h20 and nutrients against gravity in plants

What is surface tension?

property allowing liquid to resist external force

What is adhesion?

the clinging of one molecule to a different molecule

Why is adhesion an important property?

allows water to cling to the cell walls to resist the downward pull of gravity

How is adhesion possible?

water’s polarity

What is capillary action?

the upward movement of water due to the forces of cohesion, adhesion, and surface tension (occurs when adhesion is greater than cohesion)

Why is capillary action important?

important for transport of water and nutrients in plants

What is temperature control(High Specific Heat)?

h20 resists changes in temperature

How is high specific heat possible?

hydrogen bonds: heat is absorbed when they break, heat is released when hydrogen bonds form

Why is high specific heat important?

• moderates air temperature (bodies of water take in heat in the daytime and release it during the nigh time)

• stabilizes ocean temp (benefits marine life)

• organisms can resist changes in their own internal temp

Name the difference between a polar covalent bond and a hydrogen bond

polar covalent bond is a single water molecule, hydrogen bonds are when water molecules bond together

What is evaporative cooling?

water has a high heat of vaporization (molecules with the highest kinetic energy leave as a gas) - (this then causes temp regulation in water)

What happens when water has a high level of kinetic energy?

becomes a gas

Why is evaporative cooling so important?

• moderates earth’s climate

• stablizes temps in lakes and ponds

• prevents terrestrial organisms from overheating (sweaty humans)

• prevents leaves from becoming too warm in the sun

Difference between evaporative cooling and High specific heat?

The property of high specific heat states that hydrogen bonds form and break which in turn release (bonds are built) and absorb (break bonds) heat. This heat is then released through the process of evaporative cooling which in turn regulates the temp in living organisms and bodies of water.

What is density (floating ice)?

as water solidifies it expands and becomes less dense

how is density (floating ice) property possible ?

when cooled h20 molecules move too slowly to break the bonds

Why is density important?

allows marine life to survive under floating ice sheets

What type of structure do hydrogen bonds form when water becomes ice?

crystalline structure

What is a solvent?

dissolving agent in a solution

what does the phrase “water is a versatile solvent” mean?

its polar molecules are attracted to ions and other polar molecules it can form hydrogen bonds with

What is a solution?

homogenous mix of two or more substances

What is a solute?

substance that is dissolved

“like dissolves like”

“polar dissolves a polar”

Why is water able to dissolve sugars and proteins?

will form hydrogen bonds with these molecules that are polar covalent bonds. This is why water is such a versatile solvent

How does water dissolve table salt?

Oxygen atoms are attracted to the positive sodium atom and the hydrogen atoms are attracted to the negative chlorine atom

When does an ionic bond occur?

when there is a transfer of electrons from one atom to another atom forming ions

What are ions

any atom with a charge (has the opportunity to bond with other atoms)

What elements on the periodic table are metals?

1st 2 columns of the periodic table

Do metals always have a positive charge?

yes

Is hydrogen a metal?

No it is a nonmetal

What are non-metals on the periodic table?

carbon, nitrogen, oxygen, fluorine, Phosphorus, sulfur, chlorine, selenium, Bromine, Iodine

Are non-metals always negative?

Yes

What are the last column of elements

noble gases

Do noble gases bond with anything? Why or why not?

No, they fulfill the octet rule. They have no need to bond

Give an example of a cation

NA+

Give an example of anion

CI-

What is organic chemistry

the study of compounds with covalently bonded carbon

organic compounds

compounds that contain carbon and hydrogen

what are carbon chains notably made up of?

hydrogen, oxygen, and nitrogen

Can carbon form more than one covalent bond?

Yes, it can form single, double, and triple covalent bonds

What is a double bond?

chemical bond in which two pairs of electrons are shared between two atoms

Carbon uses its valence electrons to do what?

to form covalent bonds to other carbons

what are hydrocarbons?

organic molecules consisting only of carbon and hydrogen

What are organic molecules

molecules that are made up of carbon and hydrogen

Carbon chains are the _____ of most organic molecules

skeletons

What are functional groups?

chemical groups attached to the carbon skeleton that participate in chemical reactions

Carbon, nitrogen, and phosphorus build molecules that are known as……

macromolecules

Name the four classes of molecules

lipids, proteins, carbohydrates, nucleic acids

What are polymers?

chain of a specific macromolecule that are made up of repeating units that are covalently bonded to each other

What are monomers?

the repeating units that make up polymers

Briefly explain dehydration synthesis reaction

bonds two monomers with the loss of water

Briefly explain hydrolysis reaction

breaks the bonds in a polymer by adding water

What are acids

molecules that donate H+ ions to solutions. More H+ ions than OH- ions = acidic substance

• the more Hydroniums (H+) in substance the more acidic it is

Do water molecules always stay intact?

No, sometimes they split up into two ions, OH- hydroxide ion and H+ hydronium ion

What are basics?

fewer H+ ions then OH- ions = solution is basic

• the more hydroxides (OH-) a substance has the more basic it is

what is neutral?

when concentrations of H+ and OH- ions are equal

What is the most basic, neutral, and acidic?

basic = 14, neutral = 7, acidic = 0 or 1

Name the chemical formula for amino group

NH2