Chemistry Midterm (CP1)

mass

A measure of the amount of matter in an object

Volume

a measure of the space occupied by the object

Weight

A measure of the force of gravity on an object

Solid

Definite shape and volume

Liquid

A state of matter that has no definite shape but has a definite volume.

Gas

A state of matter with no definite shape or volume

States of matter

solid, liquid, gas

physical change

A change in a substance that does not involve a change in the identity of the substance

chemical change

A change in matter that produces one or more new substances

physical properties

the characteristics of a substance that can be observed or measured without changing the substance

chemical properties

Characteristic that cannot be observed without altering the substance

Words to describe physical change

boil, freeze, melt, condense, break, split, grind, cut, crush

Physical changes an be either ....

Reversible or irreversible

homogeneous mixture

A mixture in which substances are evenly distributed throughout the mixture

heterogeneous mixture

a mixture in which the composition is not uniform throughout

pure substance

A substance made of only one kind of matter and having definite properties. Cannot be physically seperated

Element

A pure substance made of only one kind of atom

Compound

A pure substance made of two or more elements chemically combined

Another name for a homogeneous mixture is a

solution

four indicators of a chemical change

1. Production of a gas

2. Absorption/release energy

3. Formation of a precipitate (solid)

4. Change in odor or in color

Law of Conservation of Mass

Matter is not created nor destroyed in any chemical or physical change

Law of Conservation of Energy

Energy cannot be created or destroyed

Reactant

A chemical substance that is present at the start of a chemical reaction

Product

A substance produced in a chemical reaction

Components of an atom

protons, neutrons, electrons

Where are protons located?

nucleus

Where are neutrons located?

nucleus

Where are electrons located?

electron cloud

Charge of protons

positive

Charge of neutrons

neutral/no charge

Charge of electrons

negative

Bohr's atomic model

Electrons can be found on specific, circular paths or orbitals around the nucleus and has a fixed energy. Cannot exist in between the rings and the rings are unequally spaced

energy level

the specific amount of energy an electron has

quantum mechanical model

the modern description, primarily mathematical, of the behavior of electrons in atoms. determines the allowed energies in an electron can have and how likely it is to find the electron in various locations around the nucleus

What does the quantum mechanical model determine about the electrons in an atom?

the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus of an atom

Quantum

the amount of energy needed to move an electron from one energy level to another

mass number

the sum of the number of neutrons and protons in an atomic nucleus (p+n)

What atom did Schrödinger study?

Hydrogen

unit of average atomic mass

amu

atomic number

number of protons

1 atomic mass unit

1/12 the mass of a carbon-12 atom

average atomic mass

the weighted average of the atomic masses of the naturally occurring isotopes of an element

relative mass

The mass of a subatomic particle compared to the mass of a proton.

atomic mass

The average mass of all the isotopes of an element

atomic mass unit

one twelfth the mass of a carbon-12 atom

hyphen notation

the mass number is written with a hyphen after the name of the element

nuclear symbol

the superscript indicates the mass number and the subscript indicates the atomic number

how do you calculate atomic mass of an element?

multiply mass of each isotope by its natural abundance (expressed as a decimal) and then add the products

what is the atomic mass for the carbon if given:

carbon-12 has a natural abundance of 98.89%

carbon-13 has a natural abundance of 1.11%

carbon-12 has an amu of 12.000 amu

carbon-13 has an amu of 13.003 amu

12.011 amu

How does Bohr's model of the atom differ from Rutherford's model?

Bohr's model states that electrons occupy orbits with fixed energy

atomic orbital

a region of space in which there is a high probability of finding an electron

what subatomic particle takes up the most volume in an atom?

electrons

the mass of an atom consists mainly of

protons and neutrons

isotopes

Atoms of the same element that have different numbers of neutrons

what happens when an electron moves to a higher energy level?

it gains energy and becomes "excited"

what happens when an electron moves from a higher energy level to a lower energy level?

loses energy by emitting light (photons)

electron configuration

the ways in which electrons are arranged in various orbitals around the nuclei of atoms

What are the three rules that govern the filling of atomic orbitals by electrons?

Electrons occupy the lowest possible energy levels. An atomic orbital can hold at most two electrons. One electron occupies each of a set of orbitals with equal energies before any pairing of electrons occurs.

What is Hund's rule?

electrons occupy orbitals of the same energy in a way that makes the number of electrons with the same spin direction as large as possible

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, each with opposite spin direction

What is the Afbau principle?

states that electrons occupy the orbitals of lowest energy first

Amplitude

Height of a wave

Wavelength

Horizontal distance between the crests

Frequency

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

hertz

The unit of frequency in 1/second or s^-1

equation for speed of light

c=λv

speed of light = wavelength x frequency

frequency and wavelength are...

inversely proportional

atomic emission spectrum

the pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains

spectrum

colored band produced when a beam of light passes through a prism

what color light has the lowest frequency and longest wavelength?

red (700nm)

what color light has the highest frequency and shortest wavelength?

violet (380nm)

frequency and energy are

directly proportional

What did Albert Einstein do in relation to chemistry?

He used Planck's quantum theory to explain the photoelectric effect (electrons re ejected when light shines on a metal).

What did Erwin Schrodinger do?

studied the hydrogen atom and used mathematical equations to describe the likelihood of finding an electron in a certain position. he developed the quantum mechanical model

What did Max Planck do?

showed mathematically that energy is proportional to frequency of radiation

E (radiant energy) = h (planck's constant) v (frequency)

what did Louis de Broglie discover?

the wavelike behavior of particles

What is the Heisenberg Uncertainty Principle?

it is impossible to determine simultaneously both the position and velocity of an electron or any other particle

f block

Lanthanides and actinides (inner transition metals)

d block

transition metals

p block

groups 13-18

s block

Groups 1 and 2, the Alkali metals and the Alkaline Earth Metals

period

A horizontal row of elements in the periodic table

group

Vertical column in the periodic table

representative elements

s and p blocks

what did Henry Moseley do?

Arranged the periodic table by atomic number

What did Dmitri Mendeleev do?

made the first periodic table, based on increasing masses

metals

good conductors of heat and electric current

metalloids

they are brittle solids, semiconductors, essential components for technology

what are the seven metalloids?

Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium

non-metals

low conductivity, not ductile, not malleable, brittle, dull, gas at room temp

Electronegativity

A measure of the ability of an atom in a chemical compound to attract electrons