PC. # 4.1 P.T. Ions & Isotopes

What is the primary contribution of Dmitri Mendeleev to chemistry?

• Discovery of the electron

• Development of the periodic table

• Formulation of the atomic theory

• Discovery of radioactivity

Which of the following best describes an ion?

• An atom with a different number of neutrons

• An atom with a different number of protons

• An atom with a different number of electrons

• An atom with a different number of nuclei

What is an isotope?

• Atoms with the same number of protons but different numbers of neutrons

• Atoms with the same number of electrons but different numbers of protons

• Atoms with the same number of neutrons but different numbers of electrons

• Atoms with the same number of protons and electrons

Which of the following is a characteristic of a neutral atom?

• It has more protons than electrons

• It has more electrons than protons

• It has an equal number of protons and electrons

• It has no neutrons

In the periodic table, what does a period represent?

• A vertical column

• A horizontal row

• A group of similar elements

• A set of isotopes

How did Mendeleev predict the existence of undiscovered elements?

• By using atomic numbers

• By leaving gaps in his periodic table

• By using electron configurations

• By using isotopic masses

Which of the following ions has a positive charge?

• Anion

• Cation

• Neutron

• Electron

How do isotopes of an element differ from each other?

• By the number of protons

• By the number of electrons

• By the number of neutrons

• By the number of nuclei

What is the significance of groups in the periodic table?

• They indicate the number of electron shells

• They indicate elements with similar chemical properties

• They indicate the atomic mass of elements

• They indicate the isotopic composition

Which of the following statements is true about neutral atoms?

• They have a net positive charge

• They have a net negative charge

• They have no net charge

• They have more neutrons than protons