Chemistry I Unit 1 Exam (Chapter 4, 5, and 25)

Which of these statements is included in Dalton’s atomic theory?

• Chemical reactions occur when atoms are separated, joined, or rearranged.

• Some but not all elements are composed of atoms.

• Atoms of the same element can have different numbers of protons.

• Atoms are divisible.

Which of the following statements is correct?

• Electrons are positively charged.

• Protons are negatively charged.

• Neutrons have no charge.

• Atoms are positively charged.

Which of the following statements is not consistent with the results obtained in Rutherford’s gold foil experiment?

• The nucleus of an atom is positively charged.

• The nucleus of an atom contains almost all the mass of the atom.

• Atoms are composed mainly of empty space.

• Electrons are contained in the nucleus of an atom.

The identity of an element can be determined on the basis of which of the following?

• the number of protons in an atom of the element

• the number of neutrons in an atom of the element

• the mass number of the element

• the atomic mass of the element

What is the atomic number and the mass number of an atom with 11 protons and 12 neutrons?

• atomic number = 11 and mass number = 12

• atomic number = 12 and mass number = 11

• atomic number = 11 and mass number = 23

• atomic number = 23 and mass number = 12

An atom of hydrogen-2 contains

• 2 protons, 2 electrons, and 2 neutrons.

• 2 protons, 2 electrons, and 4 neutrons.

• 1 proton, 1 electron, and 1 neutron.

• 1 proton, 1 electron, and 2 neutrons.

Which of the following statements is correct?

• Each vertical column of elements in the periodic table is called a period.

• The elements in any group of the periodic table have similar physical and chemical properties.

• Group 1A contains the elements hydrogen and helium.

• In the modern periodic table, elements are listed in order of increasing atomic mass.

Isotopes of the same element have

• the same number of protons but different numbers of neutrons.

• the same number of protons but different numbers of electrons.

• the same number of neutrons but different numbers of protons.

• the same number of neutrons but different numbers of electrons.

Which symbol correctly represents an element (D) whose atoms contain 15 protons and 20 neutrons?

If Z is the symbol for an element, which pair among the following represents isotopes of the same element?