Atom Prep

A student drew atomic models of four elements. Based on these drawings, which element is the least reactive?

• Neon, because it has two energy levels with eight electrons in the second level

• Chlorine, because it has three energy levels with seven electrons in the third level

• Gallium, because it has four energy levels with three electrons in the fourth level

• Tin, because it has five energy levels with four electrons in the fifth level

How many valence electrons are in an atom of each element in Group 17 in the periodic table?

• 7

• 6

• 17

• 9

Which of the following best describes an electron?

• It has no charge and about the same mass as a proton.

• It has a negative charge and much less mass than a proton.

• It has a positive charge and much more mass than a neutron.

• It has a negative charge and about the same mass as a neutron.

A researcher wants to experiment with an element that reacts like phosphorus (P) but has a greater atomic mass. Which element should the researcher select for the experiment?

• Nitrogen (N)

• Sulfur (S)

• Arsenic (As)

• Silicon (Si)

A model of an atom is shown below. An atom of which element is represented by this model?

• Boron (B)

• Carbon (C)

• Neon (Ne)

• Sodium (Na)

When trying to identify an unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with?

• The total number of neutrons in the unknown element

• The total number of particles in the nucleus of the unknown element

• The number of protons in the nucleus of the unknown element

• The number of valence electrons in the unknown element

A student is asked to identify an element that is a pale-yellow brittle solid and does not conduct electricity. At which location in this periodic table would the element most likely be found?

• 1

• 2

• 3

• 4

An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom’s nucleus?

• +25

• +30

• −25

• −30

What is the mass number of a potassium (K) atom that has 20 neutrons?

• 18

• 19

• 20

• 39

A student is studying calcium, a highly reactive element that humans need for strong bones. Which characteristic of calcium is most closely related to its chemical reactivity?

• The 20 protons in each atom of calcium

• The density of calcium, which is 1.54 g/cm3

• The atomic mass of calcium, which is 40.078 amu

• The 2 valence electrons in each atom of calcium