VALENCE ELECTRONS 8.5B

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 leve

• 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

Tags

NGSS.MS-PS1-1

A chemist made the table below to record some atomic properties of four elements.

Based on the information in the table, which conclusion about the chemical reactivity of these elements is valid?

• Boron is the most reactive because it has the most protons.

• Fluorine is the most reactive because it has 7 electrons in the outer shell.

• Silicon is the most reactive because it has an equal number of protons and neutrons

• Gallium is the most reactive because it has many more neutrons than protons.

Tags

NGSS.MS-PS1-1

Four students were asked to name the parts of an atom that determine the atom’s identity and chemical properties. The students’ responses are shown in the table below.

Which student’s responses are correct?

• Student 1

• Student 2

• Student 3

• Student 4

Tags

NGSS.MS-PS1-1

The atoms of a certain element each contain 11 protons and 1 valence electron. Which statement correctly identifies this element and describes its chemical reactivity?

• The element is fluorine, and it is not very reactive.

• The element is sodium, and it is not very reactive.

• The element is sodium, and it is highly reactive.

• The element is fluorine, and it is highly reactive.

A chemist is identifying the elements present in a sample of seawater. What characteristic of an element’s atoms always determines the element’s identity?

• The number of valence electrons

• The location of valence electrons

• The number of neutrons

• The number of protons

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 5. g 4 /cm3

• The atomic mass of calcium, which is 40.078 amu

• The 2 valence electrons in each atom of calcium

How many valence electrons are in an atom of each element in Group 15 in the periodic table?

(answer should be a number only: example- 8)

Four students were asked to complete a table for a science assignment. Each student selected one chemical element from each of four groups in the periodic table and then classified each element as a metal, a nonmetal, or a metalloid. Which table was completed correctly?

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Students were asked to identify the location of elements in the periodic table based on clues printed on game cards.

Based on the data, which periodic table shows the correct location of the four elements?

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Tags

NGSS.MS-PS1-1

Which pair of properties describes the elements in Group 18?

• They are chemically stable and liquid at room temperature.

• They have eight valence electrons and are flammable.

• They are magnetic and boil at low temperatures.

• They are gaseous at room temperature and chemically stable.