Since you want atomic (rather than molecular) anions AND 9 protons only the element with atomic number 9 is possible, i.e. Fluorine. This has really only one anionic state though, -1. So I can only suppose you mean either:
- transient unstable anions
- synthetic isotopes of Fluorine (also unstable)
- molecular rather than atomic anions
In the latter case (most likely) you could have as well as F- also e.g. NH2- or OH- as molecular (not atomic) anions with 9 protons in total.
The atomic number of Oxygen is 8, which is also the number of protons.
The atomic number of an element is equal to the number of protons in its nucleus. Given that the element has 9 protons, its atomic number is 9. Therefore, the element in question is fluorine (F), which has an atomic number of 9.
Fluorine's atomic number is 9, meaning it has 9 protons in its nucleus.
The atomic mass of an atom can be calculated by adding the number of protons and neutrons together. In this case, an atom with 8 protons and 9 neutrons would have an atomic mass of 17 atomic mass units (amu).
The atomic mass of an element is the sum of its protons and neutrons. In this case, the atomic mass would be 4 protons + 5 neutrons = 9 atomic mass units.
Chlorine anion: Cl-, Fluorine anion: F-, Oxygen anion: O2-
The atomic number of fluorine is 9. So there are 9 protons
The number of protons is equal to the atomic number. Fluorine's atomic number is 9, so Fluorine has 9 protons.
An atom with an atomic number of 9 means it has 9 protons. The atomic mass of 19 indicates the total number of protons and neutrons in the nucleus, so if the atom has 9 protons, the remaining mass comes from neutrons (19-9=10 neutrons).
An atom's atomic number gives its number of protons. Fluorine's atomic number is 9. Thus, fluorine has 9 protons.
An atom's atomic number gives us its number of protons. Fluorine's atomic number is 9. Thus, it has 9 protons.
The atomic number of Oxygen is 8, which is also the number of protons.
There are 9 protons in this fluorine atom because the atomic number (9) represents the number of protons in an atom.
The atomic number is the number of protons. It is also the number of electrons. The atomic mass equals the protons and neutrons together/weight of the nucleus. So, the atomic number would be nine, because there are 9 protons. The atomic mass would be around 19, because there would be 9 protons and 10 neutrons in the nucleus. The element you are talking about is actually Fluorine, and on the periodic table it says that the atomic mass is 18.9984032. This is because the atomic mass is usually never an exact amount. You can round this decimal place to 19, anyway.
Flourine has the atomic number of 9. The atomic number determines the number of protons in an atom of the element, so there are 9 protons.
The atomic number of any element is equal to the number of protons in its nucleus. For example, fluorine (F) has an atomic number of 9. This means it has 9 protons.
Fluorine has 9 protons per atom: The number of protons per atom is by definition the atomic number of an element, and reference to a periodic table shows that the atomic number of fluorine is 9.