PHYS Ch 12

The nucleus of an electrically neutral iron atom contains 26 protons. How many electrons does this iron atom have?

26

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

31

Which of the following best explains what is happening when an atom emits light?

An electron is dropping from a higher to a lower energy level with the difference in energy between the two being emitted as light.

Which atom is smallest

Be

The element bromine, Br (atomic number 35), has two major isotopes of similar abundance, both around 50 percent. The atomic mass of bromine is reported in the periodic table as 79.904 atomic mass units. Choose the most likely set of mass numbers for these two bromine isotopes.

Br-79, Br-81

Which element has the atomic number 9?

F (fluorine)

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

Group 2 of the periodic table

What is the valence shell?

It is the outermost shell of electrons in an atom.

Which element has the atomic number 12?

Mg

Evidence for the existence of neutrons did not come until many years after the discoveries of the electron and the proton. Give a possible explanation.

The neutron lacks an electrical charge.

Why isn't dirt listed in the periodic table?

The periodic table lists only elements made of one kind of material. Dirt is a mixture of elements and compounds.

The mass number of an element is

The sum of the protons and the neutrons

Which are older, the atoms in the body of an elderly person or those in the body of a baby?

They are of the same age, which is appreciably older than the solar system.

Does it make sense to say that a textbook is about 99.9 percent empty space?

Yes. A textbook like all material things is made up of atoms, which are considered to be 99.9 percent empty space.

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

atomic mass, 99 amu; 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 statements describes an isotope?

element with the same number of protons but a different number of neutrons

The oldest known elements in the periodic table are the ones with

odd atomic symbols because they were originally named in Latin

If two protons and two neutrons are removed from the nucleus of an oxygen atom, a nucleus of which element remains?

Carbon-12

An element is best described as a material

Consisting of only one type of atom

Should the periodic table be memorized? Why or why not?

No. The periodic table is a reference to be used, not memorized.

The most massive subatomic particle is the

Nucleus

Which atom is largest?

Rb

When we breathe we inhale oxygen, and exhale carbon dioxide, plus water vapor. Which likely has more mass, the air that we inhale or the same volume of air we exhale? Does breathing cause you to lose or gain weight?

The air we exhale has more mass; breathing causes you to lose weight

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

The atomic masses are average atomic masses