3
Only hydrogen has un-isotopic atoms without a neutron. Hydrogen can sometimes though have one or so neutrons in its isotopes. The other elements must have neutrons to keep the protons from repelling each other in the atom's nucleus.
yes (except for the two isotopes of hydrogen).
EVERYTHING except hydrogen is denser than helium.
Apart from a few, almost all elements have isotopes. They are almost similar except the number of neutrons they have.
an isotope is a different form of that element. They just have different mass numbers/ atomic mass. Therefore having the same characteristics of the atom except for an increased/decreased number of neutrons. Isotopes have the same atomic number as each other.
Only hydrogen has un-isotopic atoms without a neutron. Hydrogen can sometimes though have one or so neutrons in its isotopes. The other elements must have neutrons to keep the protons from repelling each other in the atom's nucleus.
yes (except for the two isotopes of hydrogen).
The atomic mass of an element is the average of all the isotopes of that element that exist on this earth, either naturally or artificially. An isotope is an atom that differs in the number of neutrons that it would normally have (which is usually the same as the number of protons it has, except in the case of hydrogen).
Helium. All elements have neutrons except hydrogen.
the average atomic mass is computed by summing all isotopic weights of the isotopes of that element and then dividing this by the the total number of isotopes of that element (note that isotopic mass is exactly the same as atomic weight, except for isotopes).
Most elements contain a mixture of two or more isotopes.
No. Although hydrogen is an atom, it doesn't exist by itself (except as an ion). Hydrogen gas is a hydrogen molecule made of two hydrogen atoms.
EVERYTHING except hydrogen is denser than helium.
Apart from a few, almost all elements have isotopes. They are almost similar except the number of neutrons they have.
Every nucleus of every element contains at least 1 proton. Every element except hydrogen also contains neutrons.
Lathanides all lathanides have stable isotopes except promethium, promethium is also the only radioactive lathanide element, hope that helped.
The first electron shell of any element is the one s shell. Every element except hydrogen has 2 one s electrons.