Atomic Structures of Elements

The atomic number is the number of protons in the nucleus of an atom, which determines the element's identity.

The nucleus is the central part of an atom, containing protons and neutrons, and it holds most of the atom's mass.

Valence electrons are the electrons in the outermost shell of an atom that are involved in chemical bonding.

The mass number is the total number of protons and neutrons in the nucleus of an atom.

Periods indicate the number of electron shells in the atoms of the elements in that row.

The atomic number is the number of protons, while the mass number is the total number of protons and neutrons.

Copper (Cu) has the highest atomic number among these elements.

Beryllium (Be) has the least number of main energy levels.

Main energy levels are the fixed distances from the nucleus where electrons can be found, represented as curved lines in the Bohr model.

Elements with more valence electrons tend to be more reactive, especially those with 1 or 7 valence electrons.