chem final

The nucleus of an atom is ____.

the central core and is composed of protons and neutrons

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

50 protons, 50 electrons, 75 neutrons

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

protons

The least penetrating form of radiation is ____.

alpha radiation

A reaction in which small nuclei combine to form a heavier nucleus is called ____.

fusion

All atoms of the same element have the same ____.

 

number of protons

What is the formula for sodium sulfate?

 

Na2SO4

Why do atoms share electrons in covalent bonds?

 

to attain a noble-gas electron configuration

What is the basis of a metallic bond?

 

the attraction of metal ions to mobile electrons

Which of the following diatomic molecules is joined by a double covalent bond?

O2

According to VSEPR theory, molecules adjust their shapes to keep which of the following as far apart as possible?

pairs of valence electrons

What causes water molecules to have a bent shape, according to VSEPR theory?

repulsive forces between unshared pairs of electrons

Which of the forces of intermolecular attraction is the weakest?

 

dispersion

Which of the following formulas represents a molecular compound?

SO2

Which of the following shows both the correct formula and correct name of an acid?

H3PO4, phosphoric acid

Which of the following statements is true about ions?

Cations form when an atom loses electrons.

\

What is the charge on the cation in the ionic compound sodium sulfide?

 

1+

What is the net charge of the ionic compound sodium sulfide?

0

Which of the following electron configurations is most likely to result in an element that is relatively inactive?

a filled highest occupied principal energy level

What element in the second period has the largest atomic radius?

fluorine

What types of atomic orbitals are in the third principal energy level?

*s, p,* and *d* only

Chemical equations must be balanced to satisfy ____.

 

the law of conservation of mass

The type of reaction that takes place when one element reacts with a compound to form a new compound and a different element is a ____.

single-replacement reaction

Avogadro's number of representative particles is equal to one ____.

mole

What SI unit is used to measure the number of representative particles in a substance

mole

The first step in most stoichiometry problems is to ____.

convert given quantities to moles

When two substances react to form products, the reactant which is used up is called the ____.

 

limiting reagent

When an equation is used to calculate the amount of product that will form during a reaction, then the value obtained is called the ____.

theoretical yield

What happens to the average kinetic energy of the particles in a sample of matter as the temperature of the sample is increased?

The average kinetic energy increases.

If a sealed syringe is heated, in which direction will the syringe plunger move?

out

When the vapor pressure of a liquid is equal to the atmospheric pressure, the liquid ____.

begins to boil.

Which of the following usually makes a substance dissolve faster in a solvent?

agitating the solution

\
 

When an acid reacts with a base, what compounds are formed?

a salt and water

Which of the following is a property of an acid?

sour taste

If the hydrogen ion concentration of a solution is 10*M*, is the solution acidic, basic, or neutral?

basic

In a neutral solution, the \[H\] is ____.

equal to \[OH\]

What is pH?

the negative logarithm of the hydrogen ion concentration

What characterizes a strong acid or base?

 

complete ionization in water

During a phase change, the temperature of a substance ____.

remains constant

In an exothermic reaction, the energy stored in the chemical bonds of the reactants is ____.

greater than the energy stored in the bonds of the products

The amount of heat needed to melt one mole of a solid at a constant temperature is called ____.

molar heat of fusion

A catalyst works by ____.

 

lowering the activation energy barrier

In an endothermic reaction at equilibrium, what is the effect of raising the temperature?

The reaction makes more products.