Unit 2 Review (Atoms)

Which answer most accurately describes an electron?

• located in the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  negative charge

• located inside nucleus,

  mass of 1 u,

  no charge

• located outside the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  no charge

Which answer most accurately describes a proton?

• located in the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  negative charge

• located inside nucleus,

  mass of 1 u,

  no charge

• located outside the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  no charge

Tags

NGSS.HS-PS1-8

Which answer most accurately describes a neutron?

• located in the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  negative charge

• located inside nucleus,

  mass of 1 u,

  no charge

• located outside the nucleus,

  mass of 1 u,

  positive charge

• located outside the nucleus,

  almost no mass,

  no charge

What is the atomic number of carbon?

an atom with 10 protons, 12 neutrons, and 10 electrons is a _______ atom

• calcium

• magnesium

• argon

• neon

Tags

NGSS.HS-PS1-1

Which model of the atom states that electrons exist in orbitals... regions of high probability?

• Planetary Model (Bohr)

• Plum Pudding Model (Thomson)

• Hard Sphere Model (Dalton)

• Wave Mechanical Model (work of several scientists)

• Nuclear Model (Rutherford)

Answer explanation

The Wave-Mechanical Model is the current model of the atom. It took ideas from previous models and refined them based on new information.

It says that electrons behave like waves, not simple particles.

We can define where they are likely to be found (orbitals) based on their energy, but not their exact path of travel.

This experiment discovered the electron.

• gold foil

• cathode ray

• Atomic spectra

• Decomposition of water

Answer explanation

Approximately 100 years after the original Atomic Theory of Dalton. This experiment noticed that a beam of tiny particles ... weighing much less than a hydrogen atom... could be bent toward a positive-charge plate.

This disproved the original idea that atoms are indivisible.

This experiment determined atoms to be mostly empty space, with a dense, positively-charged nucleus.

• gold foil

• cathode ray

• Atomic spectra

• Decomposition of water

Answer explanation

See image for observations and inferences of the gold foil experiment.

Tags

NGSS.HS-PS1-8

An atom of K-42 has __ protons.

• 42

• 23

• 19

• 39

• 0

Answer explanation

Atomic #19 means 19 protons...

An atom of K-42 has __ electrons.

• 42

• 23

• 19

• 39

• 0

Answer explanation

Atoms have the same number of electrons as they do protons.

Atomic #19 means 19 protons... therefore 19 electrons.

Tags

NGSS.MS-PS1-1