Ch1 Atomic structure

• A

• B

• C

• D

Helium, He, is the second element in the Periodic Table.

Tritium is the isotope of hydrogen ³H.

What is the same in an atom of ⁴He and an atom of ³H?

• the number of electrons

• the number of neutrons

• the number of protons

• the relative atomic mass

John Dalton’s atomic theory, published in 1808, contained four predictions about atoms.

Which of his predictions is still considered to be correct?

• Atoms are very small in size.

• No atom can be split into simpler parts.

• All the atoms of a particular element have the same mass.

• All the atoms of one element are different in mass from all the atoms of other elements.

The diagrams show the possible paths of subatomic particles moving in an electric field in a vacuum.

Which diagrams are correct?

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

• 1, 2 and 3

In which species are the numbers of electrons and neutrons equal?

• ⁹Be

• ¹⁹F

• ²³Na⁺

• ¹⁸O^2-

Which ion has more electrons than protons and more protons than neutrons?

• D^–

• H₃O⁺

• OD^–

• OH^–

The technetium–99 isotope (⁹⁹Tc) is radioactive and has been found in lobsters and seaweed adjacent to nuclear fuel reprocessing plants.

Which statements are correct about an atom of ⁹⁹Tc?

• It has 13 more neutrons than protons.

• It has 43 protons.

• It has 99 nucleons.

• A

• B

• C

• D

The phosphide ion ³¹P^3– and sulfide ion ³²S^2– have the same number of which sub-atomic particles?

• neutrons

• electrons

• protons

In which species are the numbers of protons, neutrons and electrons all different?

• ²⁷Al

• ³⁵Cl^-

• ³²S^2-

• ³⁹K⁺