Noble gases (except for helium which has 2 valence electrons).
Carbon has four electrons in the outermost energy level, which is energy level two. It needs eight electrons to have this energy level filled.
Outermost energy level is full if there are 8 electrons in the valence shell.
Phosphorus has 5 electrons in its outermost principal energy level.
The question is somewhat vague. If the question were written as an atom contains seven electrons in the outermost energy level and that outermost shell is a p-shell then the atom is a halogen. If the atom contains seven electrons in the outermost energy level and that outermost shell is a d-shell or f-shell then the atom is a metal.
helium
Aluminum has 3 electrons in its outermost energy level.
valence electrons are the electrons in the outermost energy level
Halogens have six valence electrons in the outermost energy level.
Sulfur has 6 electrons in its outermost energy level.
A neutral sulfur atom has 6 electrons in its outermost energy level. Sulfur has 16 electrons, with 2 electrons in the first energy level, 8 electrons in the second energy level, and 6 electrons in the third and outermost energy level.
Atoms form chemical bonds to achieve a full outermost energy level by sharing, gaining, or losing electrons. Valence electrons are the electrons in the outermost energy level of an atom, and having a full outermost energy level makes the atom more stable. This stability is achieved when there are eight electrons in the outermost energy level, known as the octet rule.
A neutral atom of magnesium has 2 electrons in its outermost energy level. Magnesium has a total of 12 electrons, with 2 electrons in the first energy level and 8 electrons in the second energy level. The outermost energy level is the second energy level in the case of magnesium.