8.5A Atomic Structure CFA

Q. 

Which of these best describes one of the subatomic particles that could be found at location X in the model of an atom shown in the illustration.

• It has a large mass but no charge

• It has a small mass and a negative charge

• It has a small mass and a positive charge

• charge

  It has no mass and an equal number of positive and negative charges

Answer explanation

The nucleus of the atom contains protons (positive charges) and neutrons (neutral/no charges).

Tags

NGSS.MS-PS1-1

Which of the following best describes an electron?

• It has no charge and about the same mass as a proton.

• It has a positive charge and much more mass than a neutron.

• It has a negative charge and much less mass than a proton.

• It has a negative charge and about the same mass as a neutron.

Answer explanation

Electrons are negatively charged subatomic particles with much less mass than a proton or a neutron.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS2-3

An atom has 25 protons, 30 neutrons, and 25 electrons. What is the charge of the atom's nucleus?

• +25

• -25

• +30

• -30

Answer explanation

The charge of the nucleus is positive and equal to the number of protons.

A model of a beryllium atom is shown in the illustration. What type of particles are found in the cloud surrounding the atom's nucleus?

• Positively charged particles and negatively charged particles

• Neutral particles and postiviely charged particles

• Negatively charged particles only

• Positively charged particles only

Answer explanation

The electron cloud, containing negatively charged electrons, surrounds the nucleus of the atom

Tags

NGSS.MS-PS1-1

 

Which statement correctly describes the location and charge of the electrons in an atom?

• The electrons are inside the nucleus and have no charge.

• The electrons are inside the nucleus and have a negative charge.

• The electrons are outside the nucleus and have no charge

• The electrons are outside the nucleus and have a negative charge.

Answer explanation

The electrons are found in the energy levels of the electron cloud surrounding the nucleus.

A chemist is identifying the elements present in a sample of seawater. What characteristic of an element's atoms always determine the element's identity?

• The number of protons

• The location of valence electrons

• The number of neutrons

• The number of valence electrons

Answer explanation

The number of protons determines the identity of the atom.