Pre-AP Chemistry Semester 1 Exam

Compound

A substance that can be separated into two or more substances only by a chemical change

Theory

A well-tested explanation for a broad set of observations is a(n)...

Higher

Compared with the electronegativities of the elements on the left side of a period, the electronegativities of elements on the right side of the same period tend to be ________

Compound

Composed of two or more substances chemically combined in a fixed proportion

Ionization energy

Energy required to remove an electron from an atom

3.2×10¹

Express the product of 4.0×10⁻² m and 8.1×10² using the correct number of significant digits

12.7 m

Express the sum of 7.68 m and 5.0 m using the correct number of significant digits?

Protons

The atomic number of an element is the total number of which particles in the nucleus?

The most unpaired electrons

The central atom in a Lewis structure is usually the atom with...

Accuracy

The closeness of a measurement to its true value is a measure of its what?

Hybridization

The combining of orbitals in an atom to form new identical orbitals

0.32 g/cm³

What is the density of an object having a mass of 8.0 g and a volume of 25 cm³?

Fluorine

What is the element with the highest electronegativity value?

Eight

What is the maximum number of electrons in the second principal energy level?

Seven

What is the maximum number of f orbitals in any single energy level in an atom?

1.0×10³ L

What is the measurement of 1042 L rounded off to two significant digits?

Atomic emission spectrum

Frequencies of light emitted by an element

Period

Horizontal row in the periodic table

They are proportional

How are frequency and wavelength of light related?

It tends to decrease

How does atomic radius change from left to right across a period in the periodic table?

It tends to increase

How does atomic radius change from top to bottom in a group in the periodic table?

The speeds are the same

How does the speed of visible light compare with the speed of gamma rays, when both speeds are measured in a vacuum?

50 protons, 50 electrons, and 75 neutrons

How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain?

Two

How many significant figures are in the measurement 0.0034 kg?

Five

How many significant figures are in the measurement 811.40 grams?

Reactant

Starting substance in a chemical reaction

Electrons

Subatomic particles that are transferred to form positive and negative ions

Element

Substance that cannot be changed into simpler substances by chemical means

Aufbau principle

Tendency of electrons to enter orbitals of lowest energy first

Kelvin temperature scale

The SI scale for temperature

Group

Vertical column in the periodic table

They have low melting points

What NOT a characteristic of most ionic compounds

Photons

What are quanta of light called?

Mass number

What does the number 84 in the name krypton-84 represent?

239 K

What is -34 C in Kelvin?

Liter

What is NOT an SI unit but often mistaken as one? (measures volume)

Kilogram

What is the SI unit of mass?

373 K

What is the boiling point of water in Kelvin?

Positive

What is the charge of a cation

Resonance

A condition that occurs when more than one valid Lewis structure can be drawn for a molecule

Scientific Method

A logical systematic approach to the solution of a scientific problem

Electron

A negatively charged subatomic particle

Mixture

A physical blend of two or more components

Proton

A positively charged subatomic particle

Experiment

A procedure that is used to test a hypothesis is a(n)...

Hypothesis

A proposed explanation for an observation is a(n)...

Periodic law

A repetition of properties occurs when elements are arranged in order of increasing atomic number

Octet Rule

A rule sating that an atom tends to gain, lose, or share electrons until its outer level s and p orbitals are filled with eight electrons (this gives an element the electron configuration of a noble gas)

Neutron

A subatomic particle with no charge

Product

A substance formed in a chemical reaction

Electronegativity

Ability of an atom to attract electrons when the atom is in a compound

Mass

Amount of matter an object contains

Crystal lattice

An orderly arrangement of ions in a three-dimensional pattern within a compound

Matter

Anything that has mass and occupies space

Electron configuration

Arrangement of electrons around atomic nucleus

Isotope

Atoms with the same number of protons but different numbers of neutrons in the nucleus of an atom

Polar covalent bonds

Bonds with unequally shared electrons

Mass; volume

Density is found by dividing _____ by ______

Homogeneous

Describes mixture with a uniform composition

Alchemists

Developed processes for separating mixtures and purifying chemicals and also designed equipment that is still in use today

Wavelength

Distance between wave crests

100 C

If the temperature changes by 100 K, by how much does it change in C?

Numbers of neutrons

Isotopes of the same element have different what?

Color, odor, malleability, hardness, melting point, boiling point

List the physical properties of a substance (six things)

Ground state

Lowest energy level

Frequency

Number of wave cycles passing a point per unit of time

Atomic mass unit

One-twelfth the mass of a carbon atom having six protons and six neutrons

Atomic orbital

Region of high probability of finding an electron

Do not

Polar bonds (DO/ DO NOT) always result in polar molecules (pick one)

Different

Polar covalent bonds result when the atoms sharing the electrons have (THE SAME/DIFFERENT) electronegativities (pick one)

Chemical reaction

Process in which substances are changed into different substances

1.54×10⁻¹⁰ m

The diameter of a carbon atom is 0.000 000 000 154 m. What is this number expressed in scientific notation?

Ionic Bond

The electrostatic attraction between two oppositely charged ions in a solid

5.008×10³ km

The expression of 5008 km in scientific notation is what?

Weight

The force of gravity on an object

Polarity

The greater the difference in electronegativity between two elements is, the greater the ________ of the resulting molecule

Absolute zero

The lowest point on the Kelvin scale

Number

The modern period table is arranged in order of increasing atomic ________

Atomic number

The number of protons in the nucleus of an element

Protons and neutrons

The particles that are found in the nucleus of an atom are...

Pure Chemistry

The pursuit of chemical knowledge for its own sake

Electron

The quantum mechanical model of the atom involves the probability of finding an ____________ in a certain position

Anion

The radius of a(n) (CATION/ANION) is greater than the radius of its neutral atom (pick one)

Formula Unit

The simplest ratio of elements in an ionic compound that describes its composition

Atom

The smallest particle of an element that retains the properties of that element

Chemistry

The study of the composition of matter and the changes that matter undergoes

Electronegativity

The tendency of an atom in a compound to attract electrons

Dependent Variable

The variable that is observed during the experiment is the...

Independent Variable

The variable that you change during an experiment is the...

Ability to rust

Three of these are physical properties. Which is not? Mass, color, melting point, ability to rust

Oil

To make a heterogeneous mixture, do you mix vinegar with water or oil?

Covalent bond

Two atoms held together in an ion or molecule by their attraction for the same pair of shared electrons

Cation

Type of ion formed by Group 2A elements

11 mm²

What is the product of 2.2 mm and 5.00 mm using the correct number of significant digits?

2.9×10³

What is the result of adding 2.5×10³ and 3.5×10²?

8.75×10³

What is the result of multiplying 2.5×10¹⁰ by 3.5×10⁻⁷?

1.1×10² mL

What is the volume of 80.0 g of ether if the density of ether is 0.70 g/mL?

2.9×10⁻⁷ m³

What is the volume of a salt crystal measuring 2.44×10⁻² m by 1.4×10⁻³ m by 8.4×10⁻³ m?

Atomic mass

What is the weighted average of the masses of the isotopes of the element?

Gas production, precipitate formation, energy transfer

What three things indicate that a chemical change may have taken place?

Sigma

What type of bond forms as a result of orbitals overlapping end to end?

Ionic bond

What type of bond would you expect in a compound of oxygen and sodium?

Solution

What's another term for a homogeneous mixture?

Least

When multiplying and dividing measured quantities, the number of significant figures in the result should be equal to the number of significant figures in the (MOST/LEAST) precise measurement (pick one)

Observation

When you use your senses to obtain information you make a(n)...

Salt water

Which is a homogeneous mixture? Salt water, beef stew, sand and water, soil

dg

Which is largest? dg, cg, ng, mg

Microliter

Which of the following is smallest? Milliliter, microliter, liter, deciliter

Erwin Schrodinger

Which scientist developed the quantum mechanical model of the atom?

Electron

Which subatomic partible plays the greats part in determining the properties of an element?

Dmitri Mendeleev

Who arranged the elements according to atomic mass and used the arrangement to predict the properties of missing elements?