1. Mendeleev organized elements in his periodic table in order of increasing ____________________.
   
   
2. You are given the melting points of three unknown substances and are asked to predict which one is an ionic compound. You would select the compound with the ____________________ melting point.
   
   
3. Two factors that determine whether a molecule is polar are the types of atoms in the molecule and the ____________________ of the molecule.
   
   
4. According to John Dalton’s observations, when elements combine in a compound
   
   

AThe ratio of their masses is always the same.

BEach element contributes an equal number of atoms.

CTheir volumes are always equal.

DTheir masses are always equal.

1. Democritus thought that matter was made of tiny particles
   
   

AOf earth, air, fire, and water.

BThat could not be divided.

CThat could be divided.

DThat were all round and smooth

1. Rutherford’s gold foil experiment provided evidence for which of the following statements?
   
   

ANegative and positive charges are spread evenly throughout an atom.

BAlpha particles have a positive charge.

CGold is not as dense as previously thought.

DThere is a dense, positively charged mass in the center of an atom.

1. Which statement about subatomic particles is true?
   
   

AProtons, neutrons, and electrons all have about the same mass.

BUnlike protons or neutrons, electrons have no mass.

CNeutrons have no charge and no mass.

DAn electron has far less mass than either a proton or neutron.

1. Which statement is true about oxygen-17 and oxygen-18?
   
   

AThey do not have the same number of protons.

BTheir atoms have an identical mass.

CThey are isotopes of oxygen.

DThey have the same mass number.

1. Which statement accurately represents the arrangement of electrons in Bohr’s atomic model?
   
   

AElectrons vibrate in fixed locations around the nucleus.

BElectrons travel around the nucleus in fixed energy levels with energies that vary from level to level.

CElectrons travel around the nucleus in fixed energy levels with equal amounts of energy.

DElectrons travel randomly in the relatively large space outside the nucleus.

1. What does the electron cloud model describe?
   
   

AThe most likely locations of electrons in atoms

BThe precise locations of electrons in atoms

CThe number of electrons in an atom

DThe mass of the electrons in an atom

1. What is the difference between an atom in the ground state and an atom in an excited state?
   
   

AThe atom in the ground state has less energy and is less stable than the atom in an excited state.

BThe atom in an excited state has one fewer electron than the atom in the ground state.

CThe atom in an excited state has more energy and is less stable than the atom in the ground state.

DThe atom in an excited state has one more electron than the atom in the ground state.

1. The usefulness of Mendeleev’s periodic table was confirmed by
   
   

Athe discovery of subatomic particles.

Bits immediate acceptance by other scientists.

Cthe discovery of elements with predicted properties.

Dthe discovery of the nucleus.

1. Atoms of the most reactive elements tend to have
   
   

Aone or seven valence electrons.

Beight valence electrons.

Cfour or five valence electrons.

Dno valence electrons.