Mass number
The mass number is like a special code that tells us how heavy or how big an atom is. Each atom is made up of tiny particles called protons and neutrons, which are in the middle of the atom in something called the nucleus. The number of protons in an atom is what gives it its identity as a specific element, but the mass number gives us an idea of how many protons AND how many neutrons are in the nucleus.
Think of it like this. Imagine you have a bunch of legos, but some of them are bigger than others. If you want to know how heavy your lego creation is, you might count how many big legos you used, plus how many small legos you used. The mass number works kind of like that - it tells us how many big "proton" legos and how many small "neutron" legos are in the atom.
The mass number is usually written as a big number next to the element symbol, like "carbon-12". This means that the carbon atom has a mass number of 12, which is the total number of protons and neutrons in its nucleus. But sometimes, different versions of the same element can have different mass numbers. These are called isotopes. For example, regular carbon has 6 protons and 6 neutrons, but there's also a carbon isotope called carbon-14 that has 6 protons and 8 neutrons. The different number of neutrons means that carbon-14 is a bit heavier than regular carbon, and it behaves slightly differently in chemical reactions.
So in summary, the mass number is like a code that tells us how many protons and neutrons are in an atom, and it helps us identify different isotopes of the same element.
Think of it like this. Imagine you have a bunch of legos, but some of them are bigger than others. If you want to know how heavy your lego creation is, you might count how many big legos you used, plus how many small legos you used. The mass number works kind of like that - it tells us how many big "proton" legos and how many small "neutron" legos are in the atom.
The mass number is usually written as a big number next to the element symbol, like "carbon-12". This means that the carbon atom has a mass number of 12, which is the total number of protons and neutrons in its nucleus. But sometimes, different versions of the same element can have different mass numbers. These are called isotopes. For example, regular carbon has 6 protons and 6 neutrons, but there's also a carbon isotope called carbon-14 that has 6 protons and 8 neutrons. The different number of neutrons means that carbon-14 is a bit heavier than regular carbon, and it behaves slightly differently in chemical reactions.
So in summary, the mass number is like a code that tells us how many protons and neutrons are in an atom, and it helps us identify different isotopes of the same element.