Unit 7 Test

What is an element?

• A simple substance that cannot be broken down into smaller parts or changed into another substance.

• A material made up of two or more different chemical substances

• An element is a mixture of different substances.

• An element is a form of energy.

Answer explanation

An element is defined as a simple substance that cannot be broken down into smaller parts or transformed into another substance, distinguishing it from compounds and mixtures.

Mark all the elements below:

• O

• Fe

• Na

• HCL

• MgBr

Answer explanation

The correct answers are O (oxygen), Fe (iron), and Na (sodium), which are all chemical elements. HCl (hydrochloric acid) and MgBr (magnesium bromide) are compounds, not elements.

Tags

NGSS.MS-PS1-1

Mark the statement that is not true.

• All atoms are only composed of neutrons.

• All elements are composed of atoms.

• All atoms have subatomic particles.

• All elements are pure substances.

Answer explanation

The statement "All atoms are only composed of neutrons" is false. Atoms consist of protons, neutrons, and electrons, not just neutrons. The other statements about elements and atoms are true.

Tags

NGSS.MS-PS1-1

• 2

• 0

• 1

• 3

Answer explanation

The chemical formula H₂O indicates there are 2 hydrogen atoms (H) in the compound. Therefore, the correct answer is 2.

Tags

NGSS.MS-PS1-1

Order the following to show the speed of the particle movement from FASTEST to SLOWEST.

• Solid

• Plasma

• Gas

• Liquid

Order the following to show the speed of the particle movement from SLOWEST to the FASTEST.

• Liquid

• Gas

• Plasma

• Solid

Which particle diagram most likely shows a solid?

• 
• 
• 

Which particle diagram most likely shows a gas?

• 
• 
• 

Which particle diagram most likely shows a liquid?

• 
• 
• 

Gas

Groups:

(a) Solid

,

(b) Liquid

,

(c) Gas

,

(d) Plasma

• moves the fastest

• most energy

• Particles are more spread out

• Moves the slowest

• Particles are packed very closely

• Vibrates in place

• Particles not as closely packed

• moves freely around gas

• Particles are free to move in all directions

• Moves faster than liquids

• Moves faster than solids

• Particles slide past each other

• More energy than liquids

• Has the least energy

• More energy than solids