Question

select the correct statement(s).
atomic number increases from left to right across a period.
atomic number represents the number of protons and the number of neutrons in a neutral atom.
chemical symbols on the periodic table are repeated.
atomic mass represents the total number of protons plus neutrons.
atomic mass increases as you move down a group.
the number of protons and the number of electrons are equal in a neutral atom.

Explanation:

• Atomic number increases from left to right across a period: In the periodic table, elements are arranged in order of increasing atomic number. As we move from left to right across a period (horizontal row), the atomic number (number of protons) of the elements increases.
• Atomic number represents the number of protons and the number of neutrons in a neutral atom: Incorrect. The atomic number (\(Z\)) represents the number of protons in an atom. In a neutral atom, the number of protons is equal to the number of electrons. The sum of protons and neutrons is the mass number (\(A\)).
• Chemical symbols on the periodic table are repeated: Incorrect. Each element has a unique chemical symbol.
• Atomic mass represents the total number of protons plus neutrons: Incorrect. The mass number (\(A\)) is the sum of protons and neutrons. Atomic mass is a weighted average of the masses of an element's isotopes.
• Atomic mass increases as you move down a group: As we move down a group (vertical column) in the periodic table, new electron shells are added. Generally, the number of protons and neutrons increases, so the atomic mass (which is related to the mass number for a single - isotope approximation) increases.
• The number of protons and the number of electrons are equal in a neutral atom: By definition, a neutral atom has no net charge. Since protons are positively charged (\(+1\) charge per proton) and electrons are negatively charged (\(- 1\) charge per electron), the number of protons must equal the number of electrons for the atom to be neutral.

Answer:

Atomic number increases from left to right across a period, Atomic mass increases as you move down a group, The number of protons and the number of electrons are equal in a neutral atom.