Chemistry Regents Review

Flashcards generated from Chemistry Regents review notes.

What is the charge and approximate mass of a proton?

Positive, 1 amu

What is the charge and approximate mass of a neutron?

No charge, 1 amu

What is the charge and approximate mass of an electron?

Negative, almost 0 amu

What particles are found in an atom’s nucleus (nucleons)?

Protons and neutrons

Where are electrons found in an atom?

Clouds (orbitals) around the nucleus

How is the mass number of an atom determined?

Sum of protons and neutrons

What is the atomic number equal to?

Number of protons in the nucleus

How do you calculate the number of neutrons in an atom?

Mass number – atomic number

In a neutral atom, what is the relationship between protons and electrons?

Number of protons equals the number of electrons

What are isotopes?

Atoms with equal numbers of protons but different neutron numbers

What are cations?

Positive ions formed by losing electrons; smaller than their parent atom.

What are anions?

Negative ions formed by gaining electrons; larger than their parent atom.

What did Rutherford's gold foil experiment reveal about the atom?

Atom is mostly empty space with a small, dense, positively charged nucleus

Who was J.J. Thompson?

Discovered the electron; plum-pudding model of the atom.

What was Dalton's model of the atom?

Solid sphere of matter that was uniform throughout.

What is the Bohr model of the atom?

Electrons in planet-like orbits around the nucleus.

Describe the current, wave-mechanical model of the atom.

Electrons in clouds (orbitals) around the nucleus.

What happens when electrons fall from higher to lower energy levels?

Emit energy as light, producing bright line spectra.

What are elements?

Pure substances composed of atoms with the same atomic number, that cannot be decomposed.

What are binary compounds?

Substances made up of only two kinds of atoms.

What are diatomic molecules?

Elements that form two atom molecules in their natural form at STP.

How do you determine significant figures when the decimal point is present?

Start counting digits from the Pacific (left) side, starting with the first non-zero digit

How do you determine significant figures when the decimal point is absent?

Start counting digits from the Atlantic (right) side, starting with the first non-zero digit

How do you determine significant figures with multiplying, dividing, adding, or subtracting measurements?

Final answer has as many digits as the measurement with the fewest number of digits. Place value.

What are solutions?

Best examples of homogeneous mixtures.

What are heterogeneous mixtures?

Have discernable components and are not uniform throughout.

What is a solute?

The substance being dissolved.

What is a solvent?

The substance that dissolves the solute.

What is average atomic mass?

Weighted average mass of all the known isotopes of an element.

What is electron configuration?

Distribution of electrons in an atom.

What are valence electrons?

Outermost electrons.

What is the empirical formula?

Simplest mole ratio among the elements in a compound.

What is an electron dot model?

Way of representing the valence electrons of an atom.

What is the kernel of an atom?

Everything in an atom except the atom’s valence electrons.

What are polyatomic ions?

Groups of atoms, covalently bonded together, with an overall charge.

What do coefficients in chemical equations represent?

Give the ratios of reactants and products in a balanced chemical equation.

How are chemical formulas written?

Charges of cations and anions neutralize each other.

How do you name binary ionic compounds?

Write the name of the positive ion (cation) first, followed by the name of the negative ion (anion) with the name ending in “-ide.”

How do you name compounds containing polyatomic ions?

Keep the name of the polyatomic ion the same as it is written in Table E.

What are Roman numerals used for when naming compounds?

Show the positive oxidation number of the cation if it has more than one positive oxidation number.

What are physical changes?

Do not form new substances; merely change the appearance of the original material.

What are chemical changes?

Result in the formation of new substances.

Where are reactants located in a chemcial equation?

Left side of the reaction arrow.

Where are products located in a chemcial equation?

Right side of the reaction arrow.

What is temperature?

Measure of average kinetic energy.

What are exothermic reactions?

Release energy

What are endothermic reactions?

Absorb energy

What are synthesis reactions?

Occur when two or more reactants combine to form a single product.

What are decomposition reactions?

Occur when a single reactant forms two or more products.

What are single replacement reactions?

Occur when one element replaces another element in a compound.

What are double replacement reactions?

Occur when two compounds react to form two new compounds.

What happens to the masses (and energy and charge) of the reactants in a chemical equation?

Is always equal to the masses (and energy and charge) of the products.

What is the gram formula mass (molar mass) of a substance?

Sum of the atomic masses of all the atoms in it.

What is Avogadro's number?

6.02 x 10^23

What is the kinetic molecular theory?

Explains the behavior of matter as particles with energy and motion.

How are the particles arranged in a solid?

Rigidly held together, closely packed in a lattice arrangement, definite shape and volume

How are the particles arranged in liquid?

Closely-spaced particles that easily slide past one another; no definite shape, but definite volume.

How are the particles arranged in gas?

Widely-spaced particles that are in random motion (collide with container to create pressure); no definite shape or volume.

What is sublimation?

Turn from a solid directly into a gas; very weak attractive forces

What happens to liquids as they evaporate?

Become gases, which create vapor pressure; vapor pressure increases as temperature increases.

What does "STP" mean?

Standard Temperature and Pressure

What is the formula for Degrees Kelvin?

Degrees Celsius + 273

What is heat?

Is a transfer of energy from a material at higher temperature to one at lower temperature.

What is heat of fusion?

The heat absorbed or released when 1 gram of a substance changes between the solid and liquid phases

What is heat of vaporization?

The heat absorbed or released when 1 gram of a substance changes between the liquid and gaseous phases

What are real gases?

Real gas particles have volume and are attracted to one another.

Why don't real gases behave like ideal gases?

Do not always behave like ideal gases.

What kind of gases are often the most ideal?

Lighter gases (with weaker attractive forces).

List three physical means of separating mixtures.

Distillation, filtration, and chromatography

What does the Periodic Law state?

The properties of the elements are periodic functions of their atomic numbers; arranged on the modern periodic table in order of increasing atomic number

What are Periods in periodic table?

Horizontal rows on the Periodic Table.

What are Groups in periodic table?

Vertical columns on the Periodic Table.

Where are metals located on the periodic table?

Left of the 'staircase' on the Periodic Table and at the bottom

Where are nonmetals located on the periodic table?

Above the 'staircase' on the Periodic Table and at the top

Where are metalloids located on the periodic table?

Border the 'staircase' on the Periodic Table

What are noble gases (Group 18)?

Unreactive and stable due to the fact that their valence level of electrons is completely filled.

What is the trend for Ionization energy in periodic table?

Increases as you go up and to the right on the Periodic Table.

What is the trend for Atomic radii in periodic table?

Decrease left to right across a period due to increasing nuclear charge. Increase as you go down a group due to increased electron energy levels.

What is Electronegativity?

Measure of an element’s attraction for electrons; increases as you go up and to the right on the Periodic Table.

What group are alkali metals located?

Group 1

What group are alkaline earth metals located?

Group 2

What group are halogens metals located?

Group 17

What group are noble gases located?

Group 18

How is energy absorbed/released in a chamical bond?

Energy is absorbed when a chemical bond breaks. Energy is released when a chemical bond forms. The greater the energy, the more stable the bond that forms.

What determines number of valence electrons in an element?

The last digit of an element’s group number.

What are Metallic bonds?

Crystalline lattice of kernels surrounded by a “sea” of mobile valence electrons.

What is considered the most stable number of valence electrons?

8 valence electrons (an octet)

What are Covalent bonds?

Form when two atoms share a pair of electrons.

What are Ionic bonds?

Occur when one atom transfers an electron to another atom when forming a bond with it.

What are Nonpolar covalent bonds?

Form when two atoms of the same element bond together.

What are Polar covalent bonds?

Form when the electronegativity difference between two bonding atoms is between 0.6 and 1.7.

Under what circumstances are Ionic bonds formed?

Form when the electronegativity difference between two bonding atoms is greater than 1.7.

What are molecular substances?

Substances containing mostly covalent bonds. They are attracted to each other by weak van der Waals or stronger hydrogen attractions.

What are Van der Waals attractive forces?

Attractive force between nonpolar molecules. Nonpolar molecules are molecules that have structural symmetry.

What are polar molecules?

Stronger forces of attraction; Lack structural symmetry.

What are Hydrogen bonds?

Attractive forces that form when hydrogen bonds to the elements N, O, or F and gives the compound unexpectedly high melting and boiling points.

What are ionic compounds?

Substances containing mostly ionic bonds. They are made of metal and nonmetallic ions. They are held together by electrostatic (ionic) forces.

What are the Properties of Ionic substances?

Hard (High melting and boiling points); Conduct electricity when molten or aqueous

What are the Properties of Covalent substances?

Soft (Low melting and boiling points); Do not conduct electricity (insulators)

What is "Like dissolves like"?

Substances tend to be soluble in solvents with similar molecular properties.