4- ELEMENTS, ATOMS, AND IONS

For chlorine choose the most appropriate natural state or description to which it applies.

• occurs in different forms called allotropes

• natural state is as a monatomic molecule

• natural state is as a diatomic molecule

A given compound _________

• always has the same numbers and types of atoms.

• may vary in the relative number and types of atoms depending on the source of the compound.

True or false? Rutherford's bombardment experiments with metal foil suggested that the particles were being deflected by coming near a large, positively charged atomic nucleus.

• True

• False

Where are neutrons found in an atom?

• in the nucleus and on the electron shell

• on the electron shell

• in the nucleus

• there are no neutrons in atoms

Do the proton and the neutron have exactly the same mass?

• The proton and the neutron have identical masses.

• The proton and the neutron have similar masses.

• The mass of the neutron is much smaller than the mass of the proton.

• The mass of the proton is much smaller than the mass of the neutron.

For an isolated atom, why do we expect the number of electrons present in the atom to be the same as the number of protons in the nucleus of the atom?

• In a free atom, positive and negative charges always balance.

• The electron charge must balance the mass of the neutrons.

• The mass number is equal to the atomic number.

• The statement is false; the number of electrons and protons do not need to be the same in an isolated atom.

• The number of electrons and protons must be equal so the atom does not fly apart.

Choose the atomic symbol for the isotope of carbon with 8 neutrons

• 
• 
• 
• 

How many protons and neutrons are contained in the nucleus of the isotope ¹³⁶₅₆Ba ?

Assuming the atom is uncharged, how many electrons are present?

See the example.

True or false? The elements are arranged in the periodic table in order of increasing mass.

• True

• False

What is needed to determine the identity of an atom?

• mass number

• number of neutrons

• total charge

• atomic number