Same =number of protons
Different =number of neutrons
(also the number of electrons outside the nucleus will be the same).
Dalton said that all atoms of one element are identical. they are chemically identical but not identical in mass. he did not know of isotopes, which are chemically identical atoms with different numbers of neutral neutrons. ex: all carbon atoms act the same chemically but some mass at 12, others at 14.
The atomic mass is the mass of an atom of that element in AMUs. (Atomic Mass Units)The atomic number, however, is equivalent to the number of protons in an atom of that element.The mass number of an atom is the total number of protons and neutrons in the nucleus of an atom. This is therefore always a whole number. The relative atomic mass of an element is the weighted average of the masses of the isotopes relative to 1/12 of the mass of a carbon-12 atom.It is a weighted average as it takes into account the relative abundances of the different isotopes (atoms of the same element but with different numbers of neutrons) of an element. This number is found in the periodic table.For example chlorine has two isotopes, 35Cl and 37Cl, in the approximate ratio of 3 atoms of 35Cl to 1 atom of 37Cl.The number of protons and neutrons in a 35Cl atom must add up to 35, the mass number. The relative atomic mass of chlorine takes into account both isotopes and is therefore 35.5.
A chemical formula gives the number ratio of the different kinds of atoms present in the compound. This means that the ratios are the same if you count in individual atoms, dozens of atoms, or molecules of atoms.
Solid - Atoms in the material are compacted and usually have some sort of crystal structure.Liquid - Atoms less compacted than in a solid, able to freely move around but still held together, mostly through intermolecular forces.Gas - Atoms very spread out, with little interaction between individual atoms.Plasma - A plasma is a gas that is heated to a point where one or more electrons is ripped of the nuclei of the material. Since the ionized nuclei are positive and the electrons negative, they repel each other and separate into polar regions. Plasmas therefore behave somewhat like a gas that has magnetic properties and is a good conductor of electricity.
Individual atoms may be heavier or lighter. Also, the spacing between atoms may vary.
Different elements with same number of neutrons are known as isotones.
Neutrons
Isotopes are atoms of an element having different number of electrons.
Atoms of all isotopes of a single element have the same number of protons in their nuclei but have different numbers of neutrons if they have different mass numbers.
Isotopes are atoms of the same element with different numbers of neutrons. Stable isotopes have a balanced number of protons and neutrons, meaning their nuclei do not decay over time. Unstable isotopes, also known as radioactive isotopes, have an imbalance of protons and neutrons, causing their nuclei to decay and emit radiation over time.
isotopes
Some elements have atoms with differing numbers of neutrons in their nuclei. These different types are called isotopes.
No - different isotopes of an element have different numbers of neutrons. All atoms of an element will have the same number of protons.
Isotopes are atoms of the same element with different numbers of neutrons, but the same number of protons.
Because of isotopes
Number of protons in the nuclei of their atoms.
Dear questioner,As an answer to your question I should mention there are atoms which have the same number of protons but are considered different. These atoms are called Isotopes. Isotopes of an element have the same number of protons but the number of Neutrons are not the same. Isotopes have the same chemical virtues but in the physical virtues related to mass they are a bit different.