Final Exam Review Chem 101

What is matter

anything that has mass and takes up space

Energy

the ability to do work or cause change, makes things move, heat up, light up, or change

what is density

mass over volume

review si unit conversions

what is a pure substance

made up of identical particles

what is a mixture

made of different particles

what are particles

general name for any structural units of a substance such as atoms, isotopes, ions, or molecules

substance

general name for any sample of matter

what is the difference between an element and a compound

an element is made of identical atoms while compounds are made of multiple elements

how do elements exist

they exist as individual or seperate stable atoms or as groups of identical atoms connectred by bonds as molecules

what is the difference between a compound and a mixture

compounds are made of elements connected by chemical bonds while mixtures made of to compounds that do not chemically react with each other.

what are the two ways compounds can exists?

exist as molecules (molecular compound) or as ions kept together by opposite charge attraction (ionic compound)

what is the difference between a homogenous and heterogenous mixture?

homogenous looks like one substance while heterogenous is not uniformly mixed

what laws led to atomic theory?

the law of conservation of mass and the law of definite proportions

what is the law of conservation of mass

mass cannot be created or destroyed in a chemical reaction

law definite propotions

a chemical compound always contains the same mass ratio.

daltons atomic theory

all matter is made of atoms, atoms of the same element are identical, atoms of different elements are different, atoms combine in whole number ratios to form compounds.

what are the subatomic particles

protons, neutrons and electrons

Proton relative charge and relattive mass

+1 and 1 amu

Neutron relative charge and relative amss

0, 1 amu

relative charge and mass of electron

-1, 0 amu

what is atomic mass

average of all isotopes mass

what is an isotope

a version of eleemnt that has the same number of protons but a different number of neutrons. this means they will have different masses

what is avogadros number used for

its a conversion factor (particles/mole

what is electromagnetic radiation

energy that travels through space as waves made of perpendicular magnetic fields

what is formula for wavelength

wavelength (lambda)= c (3.18 × 10^8 m/s)/f (frequency

higher frequency means and lower frequency

shorter wavelenght, longer wavelenght (they are inversely proportional).

now the order of magnitude for the wavelength range corresponding to the visible region of the electromagnetic spectrum (400 nm - 700 nm).

what is quantum

the amount of electromagnetic energy that can be transferred in one pulse

photon

a quantum of light

what is the photoelectric effect

emission of electrons from a metal surface when light shines on it, only a light above a certain threshold frequency can eject electrons (increasing the intensity of light increases number of electrons ejected)

energy of a photon equations

E=hv=hc/lambda (e=energy of a photon, h+ 6.626 × 10^-34 J, v=frequency, lambda = wavelenght, c= 3×10^8)

what does duality mean in terms light and electrons

light behaves as both a wave and as a particle since it consists of photons and exhibits interference and diffraction. an example of this duality is the photoelectric effect.

What is a spetrum

range of different types or wavelengths of electromagnetic radiation

what is the difference between a continous and line spectrum

a continous spectrum contains all wavelengths without interruption while line spectrum contains specific discrete wavelenghts of light.

What is the difference between an emission spectrum and an absorption spectrum

emission has a dark backgroud, (light emited electrons drop to lower energy levels) Absorption has light blackground (light is absorved electron jump to higher energy levels)

What are Bohr’s hypotheses

1) electrons move in fixed circular orbits called energy levels that are quantized, (quantized means electrons cannot exist in between them)

2) only certain orbits are allowed

3) electrons do not emit energy

4) electrons do not emit energy when in stable orbit, ONLY when the jump between levels.

Spectral lines are produced by __________ transitions.

electron

Large change in energy of a photon means what for wavelength

shorter wavelenght

Small change in Delta E means what for wavelength

longer wavelength

how are energy and frequency related in terms of proportionality

directly proportions, large E means high frequency, small E means low frequency)

When ne goes from a lower number to a higher number it is known as an _____

absorption

When n goes from a higher number to a lower number it is known as a ________.

emisssion

Energy levels get __________ as n increases

closer (so less energy)

What is the difference between the photoelectric effect and electron transitions between atomic energy levels.

In the photoelectric effect, the electron is completely knocked completely out of the atom while in atomic transitions the electron stays inside the atom, it only moves between energy leves. Also the photoelectric effect happens in metals while atomic transitions happen in all atoms. Additionally photoelectric affect needs to be greater than threshold energy while atomic energy transitions have to be exactly the energy between energy levels.

What is the quantum mechanical model of the atom

electrons can behave as so wave equations can be used to calculate their 3D trajectories.

list each subshell and the number of orbital s per subshell

s (1 orbital), p (3 orbitals), d (5 orbitals), f (7 orbitals)

Each orbital holds _________

electrons

what is n

the number of subshells

review reading periodic table, recognize families of elements (main group vs transition metals vs metalloids)

What does electron configuration

tells you which shells electrons are in, which subshells they occupy, and how many electrons are in each subshell

What is the pauli exclusion principle

a orbital can hold a maximum of 2 electrons and they must have opposite spins

paired vs unpaired electrons

paired electrons are two electrons that occupy the same orbital with opposite spins, while an unpaired electron occupies an orbital alone

what are degenerate orbitals

orbitals that have the same energy level within the same subshell.

review spdf notation and orbital diagrams

what is hunds rule

electrons will fill degenerate orbitals singly first before pairing up

what is effective nuclear charge

Zeff= atomic number (total number of protons) - number of shileding/core electrons in inner shell

how to find the number of core electrons

number of electrons (same as atomic number) - valence electrons

what is the shielding effect

the repulsion of inner electrons on outer electrons that reduces the full pull of the nucleus meaning outer electrons feel less attraction

core electrons vs valence electrons

core electrons are not in the outermost shell and do not participate in chemical bonding, they shield valence electrons from the nucleus

valence electrons are in outermost shell and can be lost gained or shared in reactions

How do you determine number of valence electrons

look at the group number or the group number last digit

why do atoms transfer electrons between each other

to achieve a stable full valence shell

when does an atom lose vs gain vs share electrons

loses if valence shell has few electrons, gains if valence shell is almost full, shares when neither losing nor gaining is easy

Why do elements in the same group have similar properties

elements in the same group have the same number of valence electrons which determine chemical behavior

cations vs anions

cation gained an electron while anions lost an electron

What is electron penetration

when electrons scoop closer to the nucleus that others since electrons dont orbit in perfect circles

How does electron penetration effect effective nuclear charge

more penetration feels more nuclear charge meaning higher Zeff, less penetration, more shielded Lower z_eff

how does penetration affect kinetic and potential energy

electrons closer to nucleus move faster so higher KE (this means more negative PE but higher KE)

how to predict charge for monoatomic ions

from left to right: +1, +2 +3 -3 -2 -1

review electron configurations and short hand electron configuration

What is atomic radius

the distance from the nucleus of an atom to the outermost electron

What affects atomic radius

effective nuclear charge since more lprotons cause a stronger pull on electrons resulting in a smaller radius.

describe the periodic trend for atomic radius

increases from right to left and top to bottom (bottom left has greatest atomic radius)

what is ionic in radius

the distance between the nucleus of an ion to its outermost electron.

True or false Ionic radius can change?

true, when an ion becomes a cation or an anion is loses or gains electrons changing the atomic radius

Describe the periodic trend for ionic radius

increases as you move down a group and from right to left (bottom left have greatest ionic radius)

What is ionization energy?

the energy required to remove one electron from a neutral atom in its gaseous state.

what does a higher effective nuclear charge mean for ionization energy?

higher ionization energy because stronger pull on electrons

What does a lower atomic radius mean for ionization energy

lower ionization energy because electron is farther from nucleus

What does a smaller atomic radius mean for ionization energy

higher ionization energy because electrons are closer to the nucleus

How does electron shielding effect ionization energy?

lower ionization energy because outer electrons are held less tightly.

describe the periodic trend for ionization energy.

ionization energy increases left to right and bottoms to top (right corner has greatest ionization energy)

removing electrons from cations requires ____________ more energy

more because already positively charged.

second ionization energy

the amount of energy required to remove a second electron from an atom after one electron has already been removed (always harder to remove the second electron) removing a second electron from a stable core electron shell is very hard! (2nd ionization energy skyrockets)

Covalent vs ionic bonds

in covalent bonds two non metals share electrons while in ionic bonds a metal transfer an electron to a nonmetal, resulting in attraction

molecular compounds vs ionic compounds

molecular compounds exist as molecules vs ionic compounds exist as 3d lattices.

True or false, all compounds (molecular or ionic) are neutral

true

what is the difference between molecular fromula and formula unit

molecular formula shows the ratio of atoms in a molecular formula while formula unit shows the ratio between opposite charges of ions

how to know the number of each type of atom per molecule

look at the subscrips

how to know the number of ions per formula unit (charge)

look at the the subscript

how to calculate the number of ions per mol of a given substance?

multiply by 6.022 × 10²3 ions/atoms

what is conductivity

the ability for a solution to allow electric current to flow through it

what is the difference between an electrolyte and a non-electrolyte

an electrolyte dissociates into ions creating a conductive solution while nonelectrolyes do not dissociate into rather dissolves as molecules so it does not conduct electricity

what is the difference between a polyatomic and monoatomic ion?

monoatomic, 1 atomic, polyatomic, multiple atoms

what is the difference between formula mass and atomic mass?

atomic mass is is the mass of one atom of at element and is measure in amu, it is the average of mass of all isotopes. Formula mass is the mass of all atoms in a formula (amu)

what is molar mass?

mass of 1 mole of a substance (unit is g/mol)

What is percent composition?

the ratio of the mass of one atom over the total mass of the compound

bonding electrons vs nonbonding electrons

bond electrons share there electrons to form a covalent bond while nonbonding electrons do not an stay as a pair of two

what is the difference between resonance structures and resonance hybrid?

resonance structures are the different lewis structures that can be written for an molecular compound while resonance hybrids are the real actrual structure of a molecule which is the true average of all possible resonance structures of a molecule