Chemistry Midterm Review
electronegativity
increases across a period and decreases down a group
hyothesis
An educated guess
polyatomic atom
An ion that is made of more than one atom
Families
Another word for groups, columns of elements on the periodic table
isotope
Atoms of the same element that have different numbers of neutrons. DIffer in mass and physical properties
Which three elements are most likely to form double or triple bonds?
C, N, O
Who conducted the gold foil experiment and what did it prove?
Physicist Ernest Rutherford established the nuclear theory of the atom with his gold-foil experiment. When he shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected. He concluded that a tiny, dense nucleus was causing the deflections.
Where are the noble gases located on the periodic table?
They are all the way to the right.
Where are metalloids located on the periodic table?
They border the stair case
Vsepr Theory
Valence-shell electron-pair repulsion theory; because electron pairs repel, molecules adjust their shapes so that valence electron pairs are as far apart as possible
Chemistry
a branch of natural science that deals principally with the properties of substances the changes they undergo and the natural law that describe these changes
precise
a measure of how close a measurement is to the correct or accepted value of the quantity being measured
Homogenous mixture
a mixture in which the composition is uniform throughout
atomic theory
all matter is composed of atoms which are indivisible
Noble Gas characteristics
are odorless, colorless, nonflammable, and monotonic gases that have low chemical reactivity. The full valence electron shells of these atoms make noble gases extremely stable and unlikely to form chemical bonds because they have little tendency to gain or lose electrons
theory
carefully thought out explanation for observations of the natural world that has been constructed using the scientific method,
What experiment led to the discovery of the electron?
cathode ray experiment
What indicates a chemical change?
color change, formation of a precipitate, formation of a gas, odor change, temperature change
volume
cubic meter (m^3)
Example of physical change
cutting, bending, dissolving, freezing, boiling and melting
Ionic Radii
decreases across a period
Atomic Radii
decreases from left to right across a period
extensive property
dependent on the size or amount of sample mass volume lenght
Aufbau Principle
dictates the manner in which electrons are filled in the atomic orbitals of an atom in its ground state.
4th spin (mg)
direction spinning in
1st principle quantum #(n)
distance away from nucleus
most of the volume of atoms is created by
electrons
Hunds Rule
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
Halogen Characteristics
form acids when combined with hydrogen, fairly toxic, combine with metals to form salts, seven valence electrons in their outer shell, highly reactive and electronegative
Transitional Metals
good conductors of heat and electricity, hammered or bent into shape easily, high melting points, hard and tough, high densities
Alkali Metals
grou 1, 1 valence electron, +1 charge
Which group of elements is most likely to form two or more ions?
group 16 elements. Their atoms have 6 valence electrons, and need 2 more to have a full valence shell of 8 electrons in order to become stable.
Alkaline Earth Metals
group 2, 2 valence electrons, +2 charge
Halogens
group 7, 7 valence electrons, -1 charge
Noble Gases
group 8, 8 valence electrons, no charge 0
ionic compound characteristics
have very high melting points and boiling points dissolve readily in water and other polar convent and are good conductors of electricity
accurate
how close your measurement is to the correct/accepted value
Why does an electron go from its ground state to its excited state?
if its given extra energy
ionization energy
increases across a period and decreases down a group
intensive property
independent of the amount of substance present density color conductivity
Mass
kilogram (kg)
Where are metals located on the periodic table?
left of staircase
Are most of the elements on the periodic table metals, metalloids, or nonmetals?
metals
Most of the mass of an atom is located in the
nucleus
3rd Magnetic (ml)
orientation in space
Where are the nonmetals on the periodic table?
right of staircase
time
second (s)
2nd Angular Movement (l)
shae
Ionic bond
the electrostatic force that holds oppositely charged particles together in an ionic compound
lattice energy
the energy released when one mole of an ionic crystalline compound is formed from gaseous ions
Alkali Metal characteristics
the high thermal and electrical conductivity, luster, ductility, and malleability that are characteristic of metals. Each alkali metal atom has a single electron in its outermost shell
Periodic Law
the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements
frequency
the number of complete wavelengths that pass a point in a given time measured in Hertz (Hz) or 1/sec
atomic number
the number of protons in the nucleus of an atom
Why is an atom electrically neutral?
the number of protons which are positive equal the number of electrons which are negative which cancels out making it neutral.
neutrons
the particles of the nucleus that have no charge
electrical orbital
the path of an electron around the nucleus of an atom
average atomic mass
the weighted average of the atomic masses of the naturally occurring isotopes of an element
Gases
they are easy to compress, (2) they expand to fill their containers, and (3) they occupy far more space than the liquids or solids from which they form.
Alkaline earth metals
two valence electrons. They have low ionization energy, low electron affinity, and low electronegativity. They are highly reactive and often form divalent cations. They are good conductors of electricity. Alkaline earth metals have an oxidation state of +2.
Light has properties of
wave and particles
Covalent Compound characteristics
weak bonds share electrons; can have single, doulbe, or triple bonds poor conductors high volatility no definite pattern of crystalline structure
Anion
A negatively charged ion
first energy level
1 subshel 2 electrons
Law of Conservation of Mass
"The mass in an isolated system can neither be created nor be destroyed but can be transformed from one form to another".
polar covalent bond
A covalent bond in which electrons are not shared equally
d shell
10 electrons fit
f shell
14 electrons fit
s shell
2 electrons fit
Pauli's Exclusion Principle
2 or more identical particles with half-integer spins (no two electrons in the same atom can have identical values for all four of their quantum numbers)
second energy level
3 subshells 6 electrons
3rd energy level
5 subshells 10 electrons
p shell
6 electrons fit
Ion
A charged atom
covalent bond
A chemical bond that involves sharing a pair of electrons between atoms in a molecule
Liquids
A liquid has a definite volume and it cannot be compressed. Liquids do not have a definite shape but acquire the shape of the vessel in which it is placed. Liquids can flow from a higher level to lower levels
Heterogenous mixture
A mixture with uneven distribution of different substances, solids, liquids, gases.
cation
A positively charged ion
element
A pure substance made of only one kind of atom
reactants
A starting material in a chemical reaction
compound
A substance made up of atoms of two or more different elements joined by chemical bonds
Density formula
D=m/v
Solid
Definite shape (rigid) Definite volume. Particles vibrate around fixed axes.
valence electrons
Electrons on the outermost energy level of an atom
Which group of elements are the most reactive nonmetals and why?
Halogens because of their valence electrons
Periods
Horizontal rows on the periodic table
What is a physcial change?
In a physical change, the material involved in the change is structurally the same before and after the change.
Chemical Change Example
Iron rusting, wood burning, baking soda and vinegar creating carbon dioxide
Who wrote the atomic theory?
John Dalton
How did Mendeleev and Mosely organize the periodic table
Mendeleev arranged elements ascendingly according to atomic masses, while Moseley arranged them ascendingly according to atomic numbers.
Length
Meter (m)
Electrons
Negatively charged particles outside the nucleus
protons
Positively charged subatomic particles found in the nucleus of an atom
Scientific Method Steps
Question, Research, Hypothesis, Experiment, Analyze the Data, Conclusion
atomic mass
The average mass of all the isotopes of an element
What do the coefficients in a chemical equation represent?
The coefficients indicate the number of each substance involved in the reaction and may be changed in order to balance the equation
wavelength
The distance between two corresponding parts of a wave measured in meters
products
The elements or compounds produced by a chemical reaction.
Milikans experiment
The force on any electric charge in an electric field is equal to the product of the charge and the electric field. Millikan was able to measure both the amount of electric force and magnitude of electric field on the tiny charge of an isolated oil droplet and from the data determine the magnitude of the charge itself.
law of definite proportions
sometimes called Proust's law, or law of constant composition states that a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation
control
standard for comparison
Law of Multiple Proportions
states that when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers