Middle School Chemistry Mid Term

Lighting a match and baking a cake are two activities that involve chemical changes. Why are these actions considered chemical changes?

• They change the state of matter.

• They create new substances.

• They change volume.

• They create energy.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which equation for the complete combustion of propane (C₃H₈) is correctly balanced?

• C₃H₈ + 3O₂ --> 2 CO₂ + 4H₂

• C₃H₈ + 7O₂ --> 3CO₂ + 4H₂O

• 2C₃H₈ + 10O₂ --> 6CO₂ + 8H₂O

• C₃H₈ + 5 O₂ --> 3CO₂ + 4H₂O

Tags

NGSS.HS-PS1-7

What type of reaction is shown below?

2KClO₃ --> 2KCl + 3O₂

• synthesis

• combustion

• decomposition

• single replacement

A sodium (Na) atom contains 11 protons, 12 neutrons, and 11 electrons. In order to make the sodium ion Na⁺, what must happen to the sodium atom?

• It must gain one electron.

• It must lose one electron.

• It must gain one proton.

• It must lose one proton.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Neutrons are particles of an atom that

• Are part of the nucleus.

• Are located outside the nucleus.

• Have positive charges.

• Have negative charges.

What do the ions K⁺, Ca²⁺, and Cl^- have in common?

• They have the same number of protons

• They are all metals

• They have the same electron configuration as Argon

• They are larger than their original atoms

Tags

NGSS.HS-PS1-1

A student has a homework assignment to identify the properties of an element based on its electron configuration. If the element has an electron configuration of 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵, which of the following is most likely a property of this element?

• Low ionization energy

• Form ions with a -2 charge

• Good electricity conductor

• Has 7 valence electrons

Tags

NGSS.HS-PS1-1

In the electron cloud model of the atom, what does the cloud represent?

• The exact orbits of the electron

• The probability of the electron location

• The average distance between the electron and the nucleus

• The minimum distance between the electron and the nucleus

Which of the following electron movements will release visible light?

• n = 4 to n = 2

• n = 2 to n = 1

• n = 1 to n = 2

• n = 1 to n = 3

Tags

NGSS.HS-PS4-3

Copper is used in electrical wiring because electrons are

• Shared between two atoms.

• Transferred between atoms forming ions.

• Delocalized and can move between many atoms.

• Held very tightly by each atom.