Element Properties (C-PS1-1)

Which element is in Group 1 and has one electron in its outermost energy level?

• Helium

• Sodium

• Oxygen

• Neon

Answer explanation

Sodium is in Group 1 of the periodic table and has one electron in its outermost energy level, making it the correct choice. Helium and Neon are in Group 18, while Oxygen is in Group 16.

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What is the term for the outermost electrons of an atom?

• Core electrons

• Valence electrons

• Protons

• Neutrons

Answer explanation

The outermost electrons of an atom are called valence electrons. They are crucial for chemical bonding and determine how an atom interacts with others, unlike core electrons, which are not involved in bonding.

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Which group on the periodic table contains elements that are all gases at room temperature and have full outer energy levels?

• Group 1

• Group 2

• Group 17

• Group 18

Answer explanation

Group 18, known as the noble gases, contains elements like helium and neon that are gases at room temperature and have full outer energy levels, making them stable and unreactive.

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How many valence electrons does an atom of oxygen have?

• 2

• 4

• 6

• 8

Answer explanation

Oxygen has 6 valence electrons, which are found in its outer shell. This is because it is in group 16 of the periodic table, where elements typically have 6 valence electrons.

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Which of the following elements is most likely to lose one electron to form a positive ion?

• Chlorine

• Potassium

• Oxygen

• Neon

Answer explanation

Potassium is an alkali metal with one electron in its outer shell, making it likely to lose that electron and form a positive ion (K+). In contrast, chlorine, oxygen, and neon are less likely to lose electrons.

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What is the maximum number of valence electrons an atom can have?

• 2

• 4

• 6

• 8

Answer explanation

The maximum number of valence electrons an atom can have is 8, which corresponds to a full outer shell, following the octet rule. This is crucial for chemical stability and bonding.

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Which element is in the same period as magnesium and has five valence electrons?

• Nitrogen

• Phosphorus

• Chlorine

• Silicon

Answer explanation

Phosphorus is in the same period (Period 3) as magnesium and has five valence electrons, making it the correct choice. Nitrogen and chlorine are in different periods, while silicon has four valence electrons.

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Which of the following elements is a halogen?

• Sodium

• Chlorine

• Argon

• Calcium

Answer explanation

Chlorine is a halogen, found in Group 17 of the periodic table. Sodium and calcium are alkali and alkaline earth metals, respectively, while argon is a noble gas. Thus, the correct answer is Chlorine.

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Which element is most likely to be chemically inert?

• Fluorine

• Argon

• Lithium

• Sulfur

Answer explanation

Argon is a noble gas with a full valence shell, making it chemically inert. In contrast, fluorine, lithium, and sulfur are reactive due to their incomplete outer electron shells.

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Which element would you expect to have similar chemical properties to sodium?

• Magnesium

• Potassium

• Oxygen

• Carbon

Answer explanation

Potassium is in the same group (alkali metals) as sodium in the periodic table, which means it shares similar chemical properties, such as reactivity and the formation of similar compounds. Magnesium, oxygen, and carbon do not share these properties.

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