Chemistry Midterm

Chemistry

Chemistry

The study of the composition, structure, and transitions of matter.

Inertia

How much force is required to move an object

condensation

Gas to liquid

Sublimation

Solid to gas

Density

The ratio of an object's mass to its volume.

The scientific method

problem solving process/method

A hypothesis is...

A suggested answer to a problem

What is true of theories?

They are part of the scientific method, they help organize a body of data, they are supported by experimental data.

What are four branches of chem?

Inorganic, organic, analytical, and biochemistry

What are the three major temperature scales?

Fahrenheit, Celsius, and Kelvin

What is the difference between a hypothesis, a theory, and a scientific law?

A hypothesis is a statement that can be tested, a theory is a highly supported hypothesis, and a law is a mathematically proven theory.

What kinds of compounds are composed of carbon?

Organic

Qualitative analysis

Determination of composition

Quantitative

A determination of the % of each element in a cpd.

How many naturally existing elements are there?

92

Can a scientific law be proven mathematically?

Yes

List and explain the several different properties of matter.

Mass- the quantity of matter, volume- how much space an object takes up, inertia- the resistance force required to move an object, impenetrability- 2 objects cannot occupy the same space simultaneously, density- the ratio of an object's mass to its volume.

What are the four states of matter?

Solids, liquids, gases, and plasma

What is an example of heterogeneous matter?

Heterogeneous matter is either a mixture or a solution. For example, mixing salt and sand together.

List and explain the steps in the scientific method.

State the problem---what you are researching, Review the Literature---read the studies that have been conducted concerning your topic, Hypothesis---a statement that can be tested, Experimenting---gather data in order to make inferences, Theory---A likely explanation for a phenomenon, Law---Mathematically proven theory

Show and explain the classification of matter.

Matter is either homogeneous or heterogeneous. Homogeneous matter is a pure substance consisting of elements and cpds. It is also the physical composition of atoms. Heterogeneous matter is impure, and consists of mixtures and solutions.

Accuracy

The nearness of a measurement to its accepted value

Precision

the agreement between measurements using the same apparatus and materials

know how to convert

Kilo-hecto-deca- |standard| -deci-centi-milla

Equivalents

1K= 2.2 lbs

1L= 1.06 qts

V r.s.=

l x w x h

V cyl. =

πr²h

Vcube=

e³

Vsphere (s)=

4/3 πr³

Density formula

Mass/volume

Fahrenheit formula

F= 9/5 c +32

Celsius formula

C=5/9 (F-32)

Kelvin formula

K=C +273

electromagnetic radiation

Forms of NRG that travel as waves at the speed of light

Frequency

the number of cycles per second

electron dot notation

a means of expressing valence electrons

Valence electrons

The electrons in the outermost shell of an atom

Octet

a stable atom having a full orbital of 8 electrons

spectra

The characteristic wavelength emitted by an excited atom

What is the unit for wavelength

angstrom

This particle has mass of 9.11 x 10⁻²⁸

electrons

What form of radiation is highest in NRG

Gamma Rays

An atom that gain an electron will have a _____ electric charge

negative

Which particles are found in the nucleus of an atom

protons & neutrons

What is the relationship between NRG of waves and wavelength?

The longer the wavelength, the lower the NRG

The _____ is the unit for frequency

Hertz (Hz)

State the Aufbau principle

Electrons must enter orbitals of lowest NRG first

Definition of the term “atom”

The smallest unit of an element/matter

The speed of electromagnetic radiation (light) is

186,000 mi/sec

State Hund’s Rule

Within a sub-level, each orbital must have one electron before they start pairing up

What are isotopes?

Atoms of the same element having a different atomic mass

List the four kinds of atomic orbitals

S, P, D, F

Explain the relationship between the energy of a wave and frequency

The higher the frequency, the higher the energy of a wave

What is the difference between the terms atomic mass and mass number?

The mass number is the mass of an atom’s protons plus it neutrons, while the atomic mass is the total mass of an atom’s protons, neutrons, and electrons

What is the formula for calculating the velocity of electromagnetic waves?

V= f x λ (velocity = frequency x wavelength)

The atomic number of an atom represents the quantity of ______

protons

List and explain the energies of the electromagnetic spectrum from highest to lowest

As you go towards the left side of the list, NRG is extremely high, frequency is extremely high, and wavelength is shorter. As you go to the right side of the list, the frequency decreases, NRG decreases, and wavelength is longer. Gamma Rays have the highest NRG and radio waves have the lowest. Everything to the left of the squiggly line is called ionizing radiation. Visible light is what humans can see, including red, orange, yellow, green, indigo, and violet.

Explain the term “hybridization” and its significance in atomic structure

Hybridization is the combination of two orbitals of near equal NRG to form a single orbital that is more stable. This is significant because hybridization provides a more simple way for atoms to become stable.

What is the difference between the continuous vs. bright line spectra of an excited atom?

The continuous spectrum is the summation of all wavelengths emitted by an excited atom, while the bright line spectrum is the individual wavelengths emitted by an atom.

periodic table-

a listing of all known elements

Cation-

a positively charged atom

Ionization NRG

the NRG used to lose an electron

noble gases

elements in group 8 that have an octet structure and are extremely stable

transition elements

elements that have more than one oxidation state

who based the periodic table on atomic number?

Moseley

What are the elements in group II called?

Alkaline earth

What indicates the quantity of valence electrons?

Group

T/F: Cations are generally larger in radii compared to their “parent” atom

False

T/F: Group VII are called halogens

True

T/F: The unit of the atomic radii is the millimeter

False

T/F: The noble gases were discovered by Sir William Ramsey

True

T/F: Halogens have very high electron affinity

True

State the periodic law

when elements are arranged by their atomic number

What is the difference between a group and a period?

A group is a vertical row and has 8

A period is a horizontal row and has 7

List five non-metals

Oxygen, nitrogen, carbon, neon, and fluorine

The _____ is the unit for atomic radii and is equal to ______

picometer; 10⁻¹⁰m

Which elements generally have “high” ionization energies?

Non-metals

Ionization NRG (increases or decreases) as one goes down a group.

DECREASES

List several synthetic materials

Cerium, europium, plutonium, curium

list several gaseous elements

Oxygen, helium, carbon, sulfur,

What are the metalloids?

metalloids are elements that have properties of both metals and non-metals

what is the unit for ionization NRG and electron affinity

kcal/mole

what is [Xe]6s²4f⁷

Eu

what is the difference between atomic number, mass number, and atomic weight?

the atomic # is the number of protons in an atom. The mass # is the amount of protons + neutrons in an atom. Atomic weight is the total mass of the atom

What are the lanthanide and actinide series of the elements?

continuation of periods six and seven

electronegativity-

an atom’s desire to share electrons

A + ____ → A⁺ + _ _ _ (explain)

NRG; 1e⁻; An atom plus NRG reacts and creates an atom with a positive charge and has one valence electron

Discuss the 8 major groups of elements.

Group I: Alkali Metals- oxidation #: +1, 1 valence electron, extremely active, extremely low ionization NRG, Xs¹

Group II: Alkaline Earth Metals- oxidation #: +2, Xs², very low ionization NRG

Group III: The Aluminum Family- oxidation #: +3, Xs²px¹, high ionization NRG

Group IV: The Carbon Family- oxidation # varies, Xs²px¹py¹, high ionization NRG

Group V: The Nitrogen Family- oxidation #: +3, -3, +5, very high ionization NRG

Group VI: The Oxygen Family- oxidation #: -2, very high ionization NRG

Group VII: The Halogens- oxidation #: -1, extremely high ionization NRG

Group VIII: The Noble Gases- oxidation #: 0, extremely stable, extremely high ionization NRG

Discuss the concept of electron affinity and explain the periodic trends for electron affinity on the table.

Electron affinity is the NRG released when an atom loses or gains an electron. The periodic trend is as you go down the periodic table, electron affinity decreases, and as you go more right it increases

Chemical bond-

an attractive force between atoms, causing them to bond

Molecular geometry-

3-D shape of a bond

Diatomic molecule-

2 of the same atom that bond

Polyatomic ion-

2 or more atoms that bond to form an ion

Ionic character-

a formula used to calculate the polarity of a covalent bond

A negatively charged ion

anion

what does a polar bond produce?

an unequal distribution of charge on a cpd (a positive and a negative region)

If two covalently bonded atoms are identical, the bond is ….

nonpolar

The electrons involved in the formation of chem bonds are called

valence electrons

When the octet rule is satisfied, the outermost _____ are filled

s & p orbitals

What molecule has a shape related to a tetrahedron (or has sp³) bonding?

CBr4