Chemistry Midterm 2021

An atom's atomic number represents the

• number of neutrons

• number of protons

• number of electrons

• number of voltrons

Which would be an example of a chemical change?

• boiling salt water

• sanding wood

• mixing vinegar and baking soda

• breaking glass

Which would be an example of a physical change?

• rotting banana

• fireworks

• crushing a can

• digesting food

Which atom below would be an isotope of sodium with a mass number of 23?

• atomic number: 12, # of neutrons: 11, # of electrons: 6

• atomic number: 11, # of neutrons: 6, # of electrons: 6

• atomic number: 11, # of neutrons: 11, # of electrons: 12

• atomic number: 11, # of neutrons: 12, # of electrons: 11

How many valence electrons does oxygen have?

• 16

• 6

• 8

• 3

Magnesium is a(n):

• alkali metal and very reactive

• halogen and very reactive

• alkali earth metal and reactive

• noble gas and very unreactive

Elements that have similar properties are located:

• in the same group

• in the same period

In his experiment, Rutherford concluded that atoms have a nucleus because

• most of the particles went straight through the foil.

• some of the particles were deflected near the front of the screen.

• some of the particles were deflected back towards the alpha source.

• not enough information is given.

Thomson concluded that cathode rays have a negative charge. Why did his experiment lead him to this conclusion?

• Opposite charges attract

• Like charges attract

• Opposite charges repel

• Like charges repel

Which particles are found in the nucleus

• electrons and protons
• neutrons and protons
• neutrons and electrons
• footballs and soccer balls

Tags

NGSS.HS-PS1-8