AP BIOLOGY

Detailed explanation-1: -Atoms of the same element have the same atomic number so the number of protons (and electrons) are same. But they have same or different mass numbers (like that for isotopes). Different mass number will have different number of neutrons.

Detailed explanation-2: -All atoms of an element have the same number of protons, and every element has a different number of protons in its atoms. For example, all helium atoms have two protons, and no other elements have atoms with two protons.

Detailed explanation-3: -All atoms of the same element have the same number of protons, but some may have different numbers of neutrons. For example, all carbon atoms have six protons, and most have six neutrons as well.

Detailed explanation-4: -All proper atoms have equal number of protons and electrons ie, all non-ions have equal number of protons and electrons. However when an atom is ionized by removing one electron, then it is positively charged and has one electron less than proton.

Detailed explanation-5: -Atoms do not always contain the same number of electrons and protons, although this state is common.