Chapter 12 Homework

If a neutral element has the following chemical symbol, how many neutrons does it have?

12

If a neutral element has the following chemical symbol, how many electrons does it have?

18

If an element has 15 protons, 16 neutrons and 15 electrons, what is the mass number of the element?

31

Which element has the atomic number 9?

F (fluorine)

What is the valence shell?

It is the outermost shell of electrons in an atom, responsible for bonding.

Which element would have chemical properties most similar to chlorine (Cl)?

Na

Why are the atomic masses listed in the periodic table not whole numbers?

The atomic masses are average atomic masses.

What does the following element description actually mean?

a uranium atom with 92 protons and 146 neutrons

If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of the element?

atomic mass, 99; Technetium

You could swallow a capsule of germanium, Ge (atomic number 32), without significant ill effects. If a proton were added to each germanium nucleus, however, you would not want to swallow the capsule because the germanium would

become arsenic.

Which of the following elements is in the fourth period?

chromium (Cr)

An element is best described as a material

consisting of only one type of atom.

Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20). This fact relates to the organization of the periodic table in that strontium and calcium are both

in group 2 of the periodic table.

Which of the following elements is an alkali metal?

lithium (Li)

Which of the following elements will most likely be shiny and malleable?

rhodium (Rh)