chem exam 2

concentration

how tells us how much solute is dissolved into a solvent

formula is amount of solute / amount of solvent

solvent

the largest component present in the largest quantity (ex water)

solute

component that is present in a smaller quantity (what is being dissolved ex. salt)

dissolving

the process of mixing a solute into a solvent

solutions

single phase homogenous mixtures

precipitate

A solid that forms from a solution during a chemical reaction. aka the resulting material that falls out of the solution

hydrogen bond

it is a special type of dipole- dipole attraction, it happens when a hydrogen is attached to a very electronegative element such as F, N, or O, it then interacts with the lone pair of electron on a nother molecule, it is weak in terms of ionic or covalent bonds, but strong in regards to inter molecular attraction. water hydrogen bond help give it a very high boiling point

Dipole

a molecule that has two poles, or regions, with opposite charges in a covalent bond, ex. polar molecules

molecular attraction in order of strongest to weakest

ion-dipole, dipole-dipole, dipole- induced dipole, induced dipole- induced dipole

ion dipole

the charge of an ion is attracted to the partial charge on a polar molecule, ex water

dipole-dipole forces

attractions between oppositely charged regions of polar molecules, ex one water molecule to another molecule

induced dipole

a dipole temporarily created in an otherwise nonpolar molecule, induced by a neighboring charge.

true or false: like dissolves like

true

induced dipole-induced dipole

Weakest intermolecular attraction. Nonpolar molecules & atoms usually have an even distribution of electrons. But, at any given time electrons can be found concentrated @ one end of the molecules. This make a temporary dipole. The larger the molecule the easier it is to induce a dipole, b/c the electrons have more shape. also known as london dispersion forces

saran wrap is an example of what intermolecular interaction

dipole - induced dipole

how can you induce a dipole in a larger neutral atom like I2

you can induce a dipole because electrons can bunch to one side w/o experiencing strong electrical repulsions among themselves.

Flurine

is very small and has little room for electrons to move, making it very unlikely to make an induced dipole.

why is methane a gas at room temperature?

It has a boiling point below room temperature as there are only weak intermolecular forces (induced dipole- induced dipole attractions)

that hold the molecules together. Little energy is needed to overcome these forces.

why is gasoline a liquid at room temperature?

because it has more than 4 carbon atoms

soluble

able to be dissolved

Insoluble

incapable of being dissolved

saturated solution

a solution that cannot dissolve any more solute under the given conditions, has dissolved the maximum amount of solute

unsaturated solution

A solution that contains less than the maximum amount of dissolved solute in a concentration; it can dissolve more solute

mole

the SI base unit used to measure the amount of a substance, 6.02x10^23

molarity

A common measure of solute concentration, # of moles of solute/ liter of solution

Physical Model

a scale model of something that is either too big or small to study in its regular size, (ex buildings, bacteria)

conceptual model

a verbal or graphical explanation for how a system works or is organized; describes something that does not have a regular shape (atoms, weather)

atom

Smallest particle of an element and the basic unit of matter

What are subatomic particles?

protons, neutrons, electrons

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

nucleon

Any subatomic particle found in the atomic nucleus. Another name for either a proton or a neutron.

atomic number

the number of protons in the nucleus of an atom

mass number

the sum of the number of neutrons and protons in an atomic nucleus

atomic mass

actual mass of atoms

photon

a quantum of light; a discrete bundle of electromagnetic energy that interacts with matter similarly to particles

quantum

a distinct packet of energy

light

a form of energy that you can see (also called electromagnetic radiation)

electromagnetic spectrum

the range of wavelengths or frequencies over which electromagnetic radiation extends.

Wavelength

the distance between the crest of one wave and the crest of the next wave or troth to troth.

The shorter the wavelength, the ________ the energy

higher

hertz

the unit of frequency, equal to one cycle per second

Isotopes

Atoms of the same element that have different numbers of neutrons, therefore they have different masses too

Ion

A charged atom

Cation

positive ion (pawsitive)

anion

A negatively charged ion

electron

A subatomic particle that has a negative charge

inner shell shielding

The tendency of inner-shell electrons to partially shield outer-shell electrons from the attractive pull exerted by the positively charged nucleus.

effective nuclear charge (Z*)

the total positive charge felt by the outer-shell electrons; Z* = (total # of protons) - (inner shell electrons)

valance shell

outermost electron shell

valance shell electrons

are electrons found in the outermost shell of the atom; electrons used in bonding (only a portion of the outer shell)

Non-bonding pairs

two paired valence electrons that tend not to form bonds

Molecule

A group of atoms bonded together, can be the same element or can be different elements

compound

a thing that is composed of two or more different elements; a mixture.

true or false:

all compounds are molecules, but not all molecules are compounds

true

Mixture

A combination of two or more substances that are not chemically combined; they keep their own properties

How can you separate mixtures?

filtration,. distilation,

Filtration

A process that separates materials based on the size of their particles.

distilation

a separtion technique that is based on differences in the boiling points of the substances involved

heterogeneous mixture

A mixture in which different materials can be distinguished easily; you can see the two different components (ex. oil and water, granite, and marble)

homogeneous mixture

A mixture in which substances are evenly distributed throughout the mixture; has identical composition throughout the mixture,

homogenous mixtures can be classified as either:

solutions or suspensions

Solution

A homogeneous mixture of two or more substances that are in the same phase

suspension

substances that are in 2 different phases, (ex. milk and blood)

what subatomic particle was the first to be discovered?

the electon

cathode ray tube

A Piece of Equipment used by Thomson to discover the electron, they were discovered because the particles were drawn toward the positive plate meaning they must have been negatively charged.

Plum Pudding Model

J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud

Rutherford's Gold Foil Experiment

he used positively charged alpha particles to shoot them into ultra thin gold, majority of the particles passed through without deflection, but some did deflect. this meant that atoms are mostly empty space with a massive, positively charged nucleus, disproved the plum pudding model

Rutherford's Atomic Model (1909)

Atoms have a small, dense, positive center (nucleus) surrounded by an "empty space" where negative charges are located.

weighted average atomic mass

average atomic mass of isotopes according to their natural abundance (mass of isotope 1 x abundance of isotope 1) + (mass of isotope 2 x abundance of isotope 2) ...

spin

when two electrons pair up in an orbital, they spin in opposite directions in order to keep from repelling each other.

opposite spin gives the electrons opposite ________ fields so they _______ each other

magnetic, attract

metallic bond

free flowing electrons between metal ions ( a sea of electrons)

alloy

A mixture of two or more metals

oscillate

(v.) to swing back and forth with a steady rhythm; to fluctuate or waver

high frequency means there is a _________ of energy

lot

white light

Mixture of all the colors in the visible spectrum (all visible light waves together)

What is the range of visible light?

380-730 nm

nanometer (nm)

10^-9 m

spectroscope

An instrument that separates light into a spectrum; used to observe the color components of light

true or false: light from an atom is a continuous badn

False

when atoms are excited by ______ or _______ they emit discrete bands of color

heat, electricity

light acts both as a ________ and a ________

wave, particle

when referring to light as a particle is it ?

a photon

the bohr model

model of the atom in which electrons move rapidly around the nucleus in paths called orbits, resembles a solar system (aka the planetary model)

probability cloud

Where the electron will most often be (95% of the time)

what does the probability cloud help predict?

the shape of an electron orbital

frequency

the number of complete wavelengths that pass a point in a given time symbol = v

What is the relationship between wavelength and frequency?

inversely proportional

atomic spectrum

a series of lines specific for each element produced by photons emitted by electrons dropping to lower energy levels

the atomic spectrum is not continuous because....

because they represent different jumps of energy that the electron could make

what are the atomic orbitals?

s, p, d, f

s orbital

Spherical shape and can hold up to 2 electrons

p orbital

• dumbbell shaped

• holds 6 electrons

d orbitals

These orbitals are diagonal, 10 electrons

f orbitals

their shapes are even more complex than s, p, or d orbitals; can hold a total of 14 electrons in 7 sub-shells