Question
4 How are elements distinguished from one another? A The number of protons. B The reaction that occurs with water. C The mass number. D The number of valence electrons.
Answer
4.1
(266 Votes)
Arabella
Master · Tutor for 5 years
Answer
A
Explanation
Elements are distinguished from one another primarily by the number of protons in their atomic nuclei. This unique number of protons, known as the atomic number, defines the identity of the element. For instance, hydrogen has one proton, helium has two, and so on. The other options, such as the reaction with water, mass number, and the number of valence electrons, do not uniquely identify an element. The mass number can vary due to the presence of isotopes, and the number of valence electrons can be similar across different elements in the same group of the periodic table.