STAAR Science

What is the difference between the number of electrons in an atom of selenium, Se, and the number of electrons of aluminum, Al?

• 21

• 52

• 13

• 34

An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is a very stable gas. How many neutrons are in this atom?

• 48

• 84

• 72

• 36

Tags

NGSS.MS-PS1-1

In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of the atom. His discovery led to the understanding that an atom consists mostly of empty space with -

• protons orbiting a dense nucleus made of electrons and neutrons

• electrons orbiting a dense nucleus made of protons and neutrons

• neutrons and protons orbiting a cloud of electrons

• electrons and protons orbiting a cloud of neutrons

Tags

NGSS.HS-PS1-8

What type of particles are found in the cloud surrounding the atom's nucleus?

• Positively charges particles and negatively charges particles

• Negatively charged particles only

• Neutral particles and positively charges particles

• Positively charges particles only

Tags

NGSS.MS-PS1-1

What is the mass number of a potassium (K) atom that has 20 neutrons?

• 18

• 19

• 20

• 39

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

• 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.

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

An atom or which element is represented by this model?

• Boron (B)

• Carbon (C)

• Neon (Ne)

• Sodium (Na)

Tags

NGSS.MS-PS1-1

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

• 5

• 15

• 7

• 10

Four students were asked to complete a table for a science assignment. Each student selected one chemical from each of four groups on 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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