8th Grade Science Checkpoint 1 Review

How do you find the amount of neutrons in an atom?

• You subtract the rounded atomic mass from the atomic number.

• You add the atomic mass to the number of protons

• You add the atomic mass to the number of electrons

• You subtract the atomic number from the number of protons

Answer explanation

The atomic mass contains the amount of protons and neutrons in the nucleus. If you subtract the atomic # (the amount of protons) then you are left with just the amount of neutrons.

If the amount of protons is the same as the amount of electrons, the atom is considered

• Positive

• Neutral

• Negative

Answer explanation

Protons have a positive charge and electrons are negative. If the amount of each is the same, the atom is neutral.

In a neutral atom, what is true

• The protons, electrons and atomic mass are all the same.

• The protons, neutrons and the atomic number are all the same.

• The protons, electrons and atomic number are all the same.

What does APE stand for

• Atomic number

  Protons

  Electrons

• Atomic Mass

  Protons

  Electrons

• A monkey

Which of these is true of the rounded atomic mass

• It is the number at the top of the periodic table.

• It is the same as the amount of Protons and Electrons

• It contains the number of protons and neutrons in the nucleus

Answer explanation

If you subtract the rounded atomic mass from the atomic number (# of protons) it will give you the amount of neutrons in the nucleus.

Which of the following tells you an atoms reactivity

• Protons

• Valence electrons

• Electrons

• Energy levels

Answer explanation

Valence electrons are the number of electrons in the outermost energy level. The first energy level can hold 2 valence electrons. The 2nd can hold 8 and the 3rd can hold 8* (For the purpose of 8th grade).

Where are the metals located on the periodic table?

• Left of the staircase

• Right of the staircase

• On the staircase

Answer explanation

The metals are to the left of the staircase.They have properties such as: being malleable (hammered into sheets), good conductors and have a metallic luster.

Group 18 are known as the Noble Gases because

• Their energy levels are full and the placement of their electrons make them unreactive.

• Their energy levels are not full making them highly reactive

• They are metals and unreactive

Answer explanation

The noble gases have full energy levels and that makes them unreactive.

What does a subscript represent?

• the number of molecules

• the number of atoms of that element in the molecule

• the chemical formula

Tags

NGSS.MS-PS1-1

Which is not an indication of a chemical change

• Gas (bubbles)

• Unexpected temperature change

• Precipitate forms

• Change in state of matter

Tags

NGSS.MS-PS1-2