8.5ABC DN 10-27-22

Which of the following best describes an electron?

• It has no charge and about the same mass as a proton.
• It has a negative charge and much less mass than a proton. 
• It has a positive charge and much more mass than a neutron.
• It has a negative charge and about the same mass as  a neutron.

An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature this element is stable. How many neutrons are in this atom? 

• 36 neutrons
• 84 neutrons
• 48 neutrons

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

• +25
• +30
• -25
• -30

Which of these best describes one of the subatomic particles that could have a mass but no charge?

• protons
• neutrons
• electrons

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

• Positively charged particles and negatively charged particles
• Negatively charged particles only 
• Neutral particles and positively charged particles 
• Positively charged particles only

In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of an atom. His discovery led to the understanding that an atom consists mostly of empty space with-

• protons orbiting a dense nucleus made of electrons and neutrons
• electrons orbiting a dense nucleus made of protons and neutrons
• neutrons and protons orbiting a cloud of electrons
• electrons and protons orbiting a cloud of neutrons

What is the mass number of a potassium (K) atom that has 20 neutrons?

• 18
• 19
• 20
• 39

Protons identify elements. What element has 5 protons? 

• Beryllium
• Boron
• Carbon
• Oxygen

Which group is more reactive, group 18 or group 1?

• group 1
• group 18

What is the periodic table mostly made of?

• metalloids
• nonmetals
• metals