chemistry castle learning answers

Which of the following substances is the best conductor of electricity?

2. Cu(s)

Isotopes of an element must have different 1. atomic numbers 2. mass numbers 3. numbers of protons 4. numbers of electrons

2. Mass numbers

As an atom becomes an ion, its mass number

Remains the same

If 75.0% of the isotopes of an element have a mass of 35.0 amu and 25.0% of the isotopes have a mass of 37.0 amu, what is the atomic mass of the element?

2) 35.5 amu

What is the total number of neutrons in an atom of Pb?

2. 125

The valence electrons represented by the electron dot diagram could be those of atoms in Group

1. 13 (IIIA)

Which subatomic particle is found in the nucleus of all isotopes of hydrogen?

1. Proton

A characteristic of most nonmetallic solids is that they are

1. brittle

Which of these elements has physical and chemical properties most similar to silicon (Si)?

1. germanium (Ge)

Rutherford's gold foil experiment illustrated that the atom

1. is mostly empty space

Compared to the entire atom, the nucleus of the atom is

1. smaller and contains most of the atom's mass

As the atoms of the Group 17 elements in the ground state are considered from top to bottom, each successive element has

1. the same number of valence electrons and similar chemical properties

Which principal energy level change by the electron of a hydrogen atom will cause the greatest amount of energy to be absorbed? 1. n = 2 to n = 4 2. n = 2 to n = 5 3. n = 4 to n = 2 4. n = 5 to n = 2

2. n = 2 to n = 5

Two atoms will always have the same atomic number if they have the same

2. number of protons

The number of neutrons in the nucleus of an atom can be determined by

2. subtracting the atomic number from the mass number

Element X has two isotopes. If 72.0% of the element has an isotopic mass of 84.9 atomic mass units, and 28.0% of the element has an isotopic mass of 87.0 atomic mass units, the average atomic mass of element X is numerically equal to

3. (72.0 × 84.9)/100 + (28.0 × 87.0)/100

An electron has a charge of

3. -1 and a smaller mass than a proton

Which atom has a nucleus that contains 13 protons and 14 neutrons?

3. Al

Neutral atoms of 35Cl and 37Cl differ with respect to their number of

3. neutrons

An atom in the ground state contains 8 valence electrons. This atom is classified as a

3. noble gas