RC 1: Day 2

An element has a metallic-grey appearance. It also has the properties of both a metal and a nonmetal. In which section of the periodic table indicated in the illustration would the element most likely be found?

• 1

• 2

• 3

• 4

Answer explanation

"Metalloids are found on the zig-zag line"

The model of the periodic table in the illustration shows the location of four elements. A student is asked to identify an element that is a pale yellow brittle solid that does not conduct electricity. At which location in this periodic table would the element most likely be found?

• 1

• 2

• 3

• 4

Answer explanation

"Nonmetals on the right"

Tags

NGSS.MS-PS1-1

A student is studying the ways different elements are similar to one another. The illustration contains diagrams of atoms from four different elements. Which two atoms are of elements in the same group in the periodic table?

• Atom 1 and Atom 2

• Atom 1 and Atom 4

• Atom 2 and Atom 3

• Atom 3 and Atom 4

Answer explanation

Elements in the same group (column) have the same number of valence electrons!!!

Tags

NGSS.MS-PS1-1

The periodic table is organized into groups and periods of elements. The characteristics of a certain group of elements are listed in the illustration. Which of these elements is in this group?

• Lithium

• Strontium

• Aluminum

• Silicon

Answer explanation

Elements with two valence electrons are found in Group 2 or 2A.

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.

Answer explanation

The elements of Group 18 are nonreactive (chemically stable) gases.

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

• 5

• 10

• 15

• 20

Answer explanation

The 5 in 15 gives you the number of valence electrons.

Tags

NGSS.MS-PS1-1

When trying to identify and unknown element, a scientist determines what other elements the unknown element reacts with chemically. Which property of the unknown element determines the other elements it reacts with.

• The total number of neutrons in the unknown element

• The total number of particles in the nucleus of the unknown element.

• The number of protons in the nucleus of the unknown element.

• The number of valence electrons in the unknown element.

Answer explanation

The number of valence electrons determines the reactivity of an element.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

A student is studying Calcium (Ca), a highly reactive element that humans need for strong bones. Which characteristics of calcium is most closely related to its chemical reactivity?

• The 20 protons in each atom of calcium

• The density of calcium which is 1.54 g/cm³

• The atomic mass of calcium which is 40.078 amu

• The 2 valence electrons in each atom of calcium

Answer explanation

The number of valence electrons in the atom determines the reactivity of the element.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

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

• The element is sodium and it is highly reactive.

• The element is fluorine and it is not very reactive

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

Answer explanation

The elements in group 1 / 1A are all highly reactive metals (except for hydrogen)

Tags

NGSS.MS-PS1-1

Four students were asked to name the parts of the atom that determine the atom's identity and chemical properties. the students responses are shown in the table. Which student's responses are correct?

• Student 1

• Student 2

• Student 3

• Student 4

Answer explanation

The number of protons determines the identity of the atom. The number of valence electrons determines the atom's reactivity (chemical properties).

Tags

NGSS.MS-PS1-1