II. Atoms and the Periodic Table

Jailah needs a replacement for lithium for a science experiment. She tries silicon, but it does not work. Using what you know about patterns in the periodic table, which advice would you give Jailah?

• Try a non-metal from the halogen group.

• Try an element in the same period as lithium.

• Try an element in the same group as lithium.

• Try a lanthanide series element.

Seth is making a slideshow about precious metals for a school project. He learns that gold (Au), silver (Ag), and copper (Cu) are often used in jewelry and coins. Seth also learns that they are all transition metals. He wants to explain the properties of these metals to his classmates. Which statement should Seth include in his slideshow?

• Gold, silver, and copper are highly reactive.

• Gold, silver, and copper have very different physical and chemical properties.

• These metals resist heat and are less reactive than group 1 and 2 metals.

• These metals have very low melting points.

A museum wants to store their valuable documents in cases that contain a gas that will protect the documents.

1. The museum director should choose __________.

2. She should not choose one of the other gases because they are too __________.

• 1. a noble gas

  2. reactive

• 1. chlorine gas

  2. smelly

• 1. oxigen gas

  2. expensive

• 1. a halogen

  2. reactive

Selena is learning about how engineers choose metals for spacecrafts. She discovers that spacecraft engineers often mix other metals with titanium. Titanium is a metal that is both lightweight and strong. It also resists corrosion. Selena wants to compare titanium with other metals. She looks at the cell from the periodic table that represents titanium.

From the information in this cell, what is the most likely number of neutrons in an atom of titanium?

• 48

• 25.90

• 26

• 47.90

What does the number 22 show?

• the atomic number

• the chemical symbol

• the atomic mass

• the name of the element

What is the atomic mass?

• the chemical symbol

• the atomic number

• the average mass number of all the isotopes of the element

• the name of the element

Classify titanium as an alkali, alkali earth, or transition metal.

• alkali

• alkali earth

• transition metal

Hydrogen gas caught fire quickly in the Hindenberg accident. In comparison, neon gas and helium gas are nonreactive. This is why helium is safe for aircraft and neon is safe for electrical signs.

Which statement best explains why helium and neon have similar chemical properties?

• They each have only one valence electron.

• They have the same number of valence electrons.

• They both have few protons.

• They are both non-metals.

Answer explanation

Neon and helium have similar chemical properties because they have the same number of valence electrons.

While neon and helium are both non-metals and have few protons, these factors do not determine reactivity.

For example, oxygen is very reactive. It is also a non-metal, and it has only eight protons.

Neon and helium have eight valence electrons, not one.

Having only one valence electron causes atoms to be very reactive.  

Ana found a tarnished silver dollar and recalled that tarnish results when metals react with oxygen or sulfur compounds in the air. She polished the silver dollar to remove the tarnish until it was shiny again. She also polished a copper bracelet and a gold ring.

What physical property of these metals makes them shiny?

• malleability

• luster

• ductility

• conductivity

Answer explanation

The

property that makes silver, copper, and gold shiny is luster.

A substance has high luster when it is reflective.

The other answer choices are not related to a material’s ability to reflect light.

Conductivity has to do with the transfer of heat or electricity.

Ductility is the ability to be drawn out into a thin wire. Malleability is the ability to be hammered or rolled into thin sheets.

Tanya is learning about the chemicals involved in breathing. Oxygen gas, water vapor, and carbon dioxide are all compounds formed by the chemical reactions between nonmetal elements.

Which statement can Tanya correctly make about the chemical properties of nonmetals?

• Nonometals are poor conductors of heat and electricity.

• Many nonmetals react with both metals and nonmetals.

• Many nonmetals are gases at room temperature.

• Nonmetals react only with other nonmetals.

Answer explanation

Even though the chemicals involved in breathing only include nonmetal elements, many nonmetals react with both metals and nonmetals.

For example, halogens are nonmetals, and they form many different compounds with group 1 and 2 metals.

It is true that nonmetals are poor conductors of heat and electricity and that many are gases at room temperature, but these choices refer to physical properties, not chemical properties.