Helium - 4 isotope has 2 protons and 2 neutrons.
Its atomic number is 2 (the number of protons). Atomic number is the number of protons in the atom of an element and it identifies the element. All the isotopes of an element have the same atomic number (same number of protons). So, all the isotopes of hellium have 2 protons.
The number 4 that identifies the helium - 4 isotope is the mass number, i.e. the number of protons plus the number of neutron. So, helium-4 isotope has 2 protons and 2 neutrons. While, other isotopes of helium have 2 protons but different number of neutrons.
The atomic number enable us to deduce the number of electrons in an atom because the atoms are neutral, which implies that the positive and negative charge are equal. Given that the magnitude of the charge of electons and protons are equal but the sign is opposed (protons are positve and electrons are negative) the number of electrons in the atom equals the number of protonts. That is why the atomic number is also the number of electrons of the atom.
Answer:
Calcium is heavier a little bit
14.626 Gallons because yeah dhhsjsjshshsh
Answer:
The change in enthaply when 10.0 g of nitrogen triiodide decomposes is -3.67 kJ.
Explanation:
Enthalpy of the reaction when 2 moles of nitrogen triiodide decomposed =
Enthalpy of the reaction when 1 moles of nitrogen triiodide decomposed :
Mass of nitrogen triiodide decomposed = 10.0 g
Moles of nitrogen triiodide = 
Change in enthaply when 0.02532 moles of nitrogen triiodide decomposed:
