The Atom

How was the Thomson model different from the Bohr model that followed it?

• The Bohr model did not include positive charges in the atom.
• The Bohr model showed electrons surrounding the positive nucleus.
• The Bohr model consisted of a single, solid mass with no smaller particles.
• The Bohr model showed neutrons in a cloud surrounding the negative nucleus.

An atom’s mass number is 210 and its atomic number is 85. How many neutrons does the atom have?

• 85
• 295
• 210
• 125

Marcus wants to use two objects to compare the sizes of a proton and an electron. If he uses a basketball for a proton, which object would best represent an electron? 

• a beach ball
• a bowling ball
• a pea
• a soccer ball

Which of these is the smallest particle to retain the properties of an element?

• an atom
• a proton
• a neutron
• an electron

Which statement is supported by the atomic theory?

• Atoms are made up of smaller particles called molecules.
• Atoms are easily destroyed when matter is cooled or heated.
• Atoms come in different sizes, but most are visible using a simple hand lens.
• Atoms combine to make all the substances on Earth.

Which group lists the parts of an atom from the most massive to the least massive?

• proton, nucleus, electron
• nucleus, proton, electron
• electron, nucleus, proton
• nucleus, electron, proton

Calcium is an element. What is the smallest particle of calcium that has all the chemical properties of calcium?

• an electron from a calcium atom
• an atom of calcium
• a molecule that contains calcium
• a proton from a calcium atom

The current model of the atom shows electrons in a cloud surrounding the nucleus. How does the electron cloud model differ from the Bohr model?

• The electron cloud shows there is not empty space in an atom.
• The electron cloud shows that electrons do not have a negative charge.
• The electron cloud shows a region in which electrons are likely to be found.
• The cloud shows that all the electrons combine together to form one mass.

Think about a wooden chair and a balloon. What do these two objects always have in common?

• Both are made of atoms.
• Both have the same mass number.
• Both are made of the same kind of atom.
• Both are made of the same number of atoms.

An atom of lead has the atomic number 82 and a mass number of 207. How many neutrons does this atom of lead have?

• 82
• 125
• 289
• 207