AP Bio - Chapter 2 (Chemistry)

Atoms

the smallest unit of matter that contains all of the chemical properties of a certain element. For example, a  carbon atom exhibits the properties of carbon.

made of two regions: nucleus (with protons and neutrons) and outermost region (with electrons)

Isotopes

one or more types of an element that have different numbers of neutrons 

some elements have naturally occuring ________

radioactive ones emit neutrons, protons, and electrons to attain a more stable atomic configuration (lower level of potential energy)

Carbon dating

C^14 is an isomer of carbon that is radioactive (naturally occurs)

used to figure out the date of living things’ life

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Periodic Table

a chart of the elements that tells the atomic number and atomic mass of each element; gives information about the properties of each element

made by Dmitri Mendeleev

organized according to atomic # and arranged in rows and columns based on shared chemical and physical properties

Chemical reactivity

the ability to combine and to chemically bond with each other

Molecules

two or more atoms that are chemically bonded together

Bohr Model

shows the atom as a central nucleus containing protons and neutrons, with the electrons in circular orbitals at specific distances from the nucleus

orbits form electron shells/energy levels

fill the orbitals closest to the nucleus first then move outward

multiple orbitals of equal energy= filled with one electron in each energy level before a second electron is added

electrons in outermost shell determine the stability of the atom and its tendency to form chemical bonds

\*see pg. 59 diagram in textbook

Orbitals

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inside shells are subshells (s, p, d, f) ex: Li is 1s²2s¹

be able to look at a drawing and tell if it is correct.

the area that contains the electrons outside of the nucleus 

Electron configuration

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the arrangement of electrons in an atom’s electron shell. Example: 1s^2,

2s^2, 2p^6 is Neon

Reactants

molecule that is on the left side of a chemical equation

Reversible chemical reactions

chemical reaction where the product may turn back into the reactants if their concentration is great enough

back and forth continues until equilibrium is reached

shown by a double headed arrow

Equilibrium of reactants and products 

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can only put numbers in front of elements, cannot change the subscripts

a written chemical reaction with the number of each type of atom equal on both sides of the equation (both on the product side and the reactant side)

Ionic bonds

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a chemical bond that happens between ions with differing charges (cations and anions) 

when an atom gives away an electron or gains an electron

create a zero net charge

Electrolytes

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 ion needed for nerve communication, muscle contractions, and water balance in the body. 

exs: sodium, potassium, and calcium

Covalent bonds

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type of strong bond formed when valence electrons are shared between two atoms of the same or different elements

more common than ionic bonding

ex: formation of water molecules

Single and double covalent bonds

one electron shared, two electrons shared

the more covalent bonds between two atoms, the stronger their connection

Polar covalent bonds

 type of covalent bond where their is an unequal sharing of electrons, resulting in the creation of a slightly positive and slightly negative charged areas of the molecule

due to differences in electronegativity

ex: water (hydrogen atoms have a partial positive charge, oxygen has a partial negative charge) polarity allows for the formation of hydrogen bonds between adjacent water molecules= unique properties

hydrogen bonding

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a weak type of bond that is between a slightly positively charged hydrogen atom and a slightly negatively charged atom in other molecules

ex: water, DNA

Water properties

polar

high heat capacity

high kinetic energy

high heat of vaporization

hydrogen bonds

cohesive

adhesive

capillary action

universal solvent

pH is 7

states of water (gas, liquid, solid)

pH

paper used is called litmus paper

based on water

stands for power of hydrogen

scale ranging from 0 to 14 that is proportional to the amount of hydrogen ions in a solution

acidity (1-6) or alkaline (8-14)

Buffers

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substance that stops a change in pH by absorbing or letting go of hydrogen or hydroxide ions. Example: bicarbonate in blood 

maintains the correct pH (homeostasis)

internal pH of the body is between 6.5 and 7.5

is a divided compound

ex: peptobismol or antacids combat excess stomach acid

Isomers

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molecules that differ from one another even though they share the same chemical formula; the arrangement of their atoms are different 

ex: glucose and fructose are both C6H12O6 but their arrangement is different

structural ones differ in the placement of their covalent bonds (butane and isobutane)

geometric ones differ in how their bonds are made to the surrounding atoms

Enantiomers

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 molecules that share overall structure and bonding patterns but differ in how the atoms are arranged three-dimensionally (they mirror each other) 

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proton

positively charged particle that stays in the nucleus of an atom; has a mass of one amu and a charge of 1+

shown by atomic number

count will not change and will always match the atomic number unless the element is bombarded or decays

neutron

subtract atomic number (protons) from atomic mass

uncharged particle that stays in the nucleus of an atom; has a mass of one amu

electrons

shown by atomic number (same as protons)

negatively charged subatomic particle that remains outside of the nucleus, orbiting around the nucleus; has no mass and a negative charge of -1 

n

energy level sublevels

ex: 1n is the first energy level (closest to the nucleus)

part of the Bohr model

octet rule

atoms are most stable when they contain eight electrons in their outermost shell

valence shell and number

the outermost shell of an atom

Products

molecule that is on the right side of a chemical equation

irreversible chemical reactions

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when reactants in a chemical reaction form an irreversible product. 

cations

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positive ion that is formed by an atom losing one or more electrons 

anions

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always from -ide at the end

negative ion that is made by an atom gaining one or more electrons. Example: chloride (CL-) 

Nonpolar covalent bonds

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type of covalent bond where atoms share electrons between them equally

how to calculate pH

power of hydrogen (H+)

examples:

pH 7 is 1 times 10^-7 (means there are 7 OH- and 7 H+)

pH 3 is 1 times 10^-3 (means there are 11 OH- and 3 H+)

pH 12 is 1 times 10^-12 (means there are 2 OH- and 12 H+)

body

the amount of carbon in your ________ will stay the same as the atmosphere (homeostasis). will occur until you die, then carbon will turn back into nitrogen (which is how carbon dating works--→ you measure the amount of nitrogen in something)

N^14 in the atmosphere. Nitrogen usually is 7 electrons and protons. when c14 becomes n14, the unstable atom’s nucleus releases radiation

polarity of water

needs to bond in a mickey mouse shape because of its uneven charge

oxygen is more electronegative than hydrogen= its more likely that a shared electron would be found near the oxygen nucleus than the hydrogen nucleus

high heat capacity

due to water’s hydrogen bonds

heat is energy and energy is a calorie

calorie- heat needed to raise the temp. of 1 g of water 1 degree

When using celsius, at 100 degrees to raise water

high kinetic energy

kinetic energy- movement energy

when water boils, molecules move and break their bonds

high heat of vaporization

due to water’s hydrogen bonds = greater temp. stability

you need more energy to raise temp. from 99 to 100 than you do to raise temp. from 32 to 33

the amount of energy needed to change one gram of a liquid substance to a gas

hydrogen bonds

weak

cohesive

molecules in water are attracted to each other

surface tension creates miniscus

soap breaks surface tension

adhesive

molecules in water are attracted to surfaces

molecules in water are more strongly attracted to the charged surface of something than they are to the other water molecules

capillary action

attraction of water molecules together causes movement

ex: drinking through a straw, spilling water onto a paper towel

universal solvent

almost every substance will dissolve in water

hydrogen bonds allow ions and other polar molecules to dissolve

ex: salt in water

Avogaders Number

one mole of water = 6 time 10^23 (lots of zeros)

low pH

lots of H+, less OH-

high pH

lots of OH-, less H+

subshell shapes

chemical reaction

the ability to combine and to chemically bond with something else