Fall 23-24 DCA

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

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

The nucleus of an atom contains which subatomic particles?

• protons and electrons

• protons and neutrons

• electrons and neutrons

• protons, electrons, and neutrons

Which subatomic particle has a negative charge?

• proton

• neutron

• electron

• cybertron

An atom has 12 protons, 14 neutrons, and 12 electrons. What is the atomic number of this element?

• 24

• 26

• 12

• 38

The picture shows part of the periodic table. Which pair of elements are in the same period?

• La and Ru

• Ra and Sg

• Y and Os

• K and Mg