Identifying Periodic Table Elements by Characteristics

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

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NGSS.MS-PS1-1

NGSS.MS-PS1-2

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.

Element R and Element Q have the same number of valence electrons. These elements both have similar chemical behavior, but Element R has fewer energy levels than Element Q. Which statement best describes the positions of the two elements in the periodic table?

• The two elements are in the same group, with Element Q at the top of the group and Element R at the bottom.

• The two elements are side by side in the same period, with Element Q to the left of Element R.

• The two elements are in the same group, with Element R just above Element Q.

• The two elements are in the same period, with Element R the first element in the period and Element Q the last element.

Tags

NGSS.MS-PS1-1

Using the Periodic Table, what element has an atomic number of 8? (a)  

• Oxygen

• Hydrogen

• Helium

• Neon

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NGSS.MS-PS1-1

Using the Periodic Table, which symbol represents an element that has 26 protons? (a)  

• Fe

• Ca

• Ar

• He

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NGSS.MS-PS1-1

Which of the following statements about noble gases is true?

• They readily form compounds with other elements.

• They have complete outer electron shells.

• They are highly reactive with water.

• They are typically found in liquid form at room temperature.

Which of the following elements is a noble gas and is known for its lack of reactivity due to having a full valence shell?

• Oxygen

• Helium

• Sodium

• Chlorine

Name this group: These elements have a full valence shell and are happy not to "play" with any other elements.

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Tags

NGSS.MS-PS1-1

Which of the following statements is true about elements in the same group of the periodic table?

• They have the same number of protons.

• They have similar chemical properties.

• They have the same atomic mass.

• They are all metals.