Reactivity and Periodic Table STAAR Bootcamp W5

An atom would become a different element if which characteristic changed?

• The number of protons

• The number of neutrons

• The number of energy levels

• The number of valence electrons

Answer explanation

An atom would become a different element if the number of protons changed. The number of protons determines the atomic number, which defines the element.

Sodium and lithium have similar chemical properties. What characteristic of these elements explains why they are chemically similar?

• Their atoms both have one valence electron.

• Their atoms both have more neutrons than protons.

• Their atoms have the same number of energy levels.

• Their atoms contain equal numbers of protons and electrons.

Answer explanation

Sodium and lithium are chemically similar because their atoms both have one valence electron.

A student prepared diagrams to model atoms of two elements. Atoms of which two elements are represented by these models?

• Oxygen, O, and neon, Ne

• Fluorine, F, and neon, Ne

• Silicon, Si, and phosphorus, P

• Beryllium, Be, and boron, B

Answer explanation

The correct choice is Beryllium, Be, and boron, B. These two elements are represented by the models of atoms.

Tags

NGSS.MS-PS1-1

Which pair of elements has reactivity that is similar to chlorine, Cl?

• Fluorine, F, and argon, Ar

• Fluorine, F, and iodine, I

• Sulfur, S, and bromine, Br

• Sulfur, S, and argon, Ar

Answer explanation

The pair of elements that has reactivity similar to chlorine, Cl, is fluorine, F, and iodine, I. They are both halogens and have similar chemical properties.

Atoms of which two elements have a combined total of 23 protons?

• Sodium, Na, and magnesium, Mg

• Boron, B, and carbon, C

• Copper, Cu, and zinc, Zn

• None of these

Answer explanation

The correct answer is Sodium, Na, and magnesium, Mg. These two elements have a combined total of 23 protons.

Tags

NGSS.MS-PS1-1

Students collected data on five elements. Their data are shown in the table. Which element has the same number of energy levels as lithium?

• Beryllium

• Sodium

• Magnesium

• Potassium

Answer explanation

Lithium and Beryllium both have 2 energy levels, making Beryllium the element with the same number of energy levels as lithium.

Tags

NGSS.MS-PS1-1

Which element has chemical properties that are most similar to the chemical properties of sulfur, S?

• Silicon, Si

• Chlorine, Cl

• Selenium, Se

• Phosphorus, P

Answer explanation

Selenium, Se has chemical properties that are most similar to sulfur, S.

Which pair of elements are nonmetals and gases at room temperature and normal atmospheric pressure?

• Fluorine, F, and chlorine, Cl

• Boron, B, and aluminum, Al

• Hydrogen, H, and cesium, Cs

• Cobalt, Co, and nickel, Ni

Answer explanation

Fluorine (F) and chlorine (Cl) are nonmetals and gases at room temperature and normal atmospheric pressure. They are the correct choice.

One of the properties that makes copper, Cu, useful for household wiring is its ability to conduct electricity. Which other element is most likely to conduct electricity?

• Gold, Au

• Radon, Rn

• Bromine, Br

• Nitrogen, N

Answer explanation

Gold, Au is the most likely element to conduct electricity. It has similar properties to copper, making it a good choice for household wiring.

Tags

NGSS.MS-PS2-3

A scientist performs tests on a sample of an element. The element is a shiny solid that conducts electricity and heat. The scientist is able to bend and flatten the sample when pressure is applied to it. Based on this information, the element could NOT be a member of which group on the periodic table?

• Group 2

• Group 8

• Group 12

• Group 18

Answer explanation

The element could not be a member of Group 18 because it conducts electricity and heat, and can be bent and flattened under pressure.