Same element. Different numbers of neutrons.
Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
Carbon-12 has 6 neutrons. Carbon-14 has 8 neutrons. Both have 6 protons, so both are carbon.
Relative atomic mass (Ar) is an average that takes account of how common each isotope is. Abundance means how much of each isotope is present.
A more common isotope has more effect on the average. This is why relative atomic mass is often a decimal. It has no units.
The scale compares atomic masses with carbon-12, which has a relative mass of exactly 12.
Use these rounded abundances: 75% chlorine-35 and 25% chlorine-37.
For percentages, multiply each mass number by its percentage, add the results, then divide by 100.
Check: 35.5 is between 35 and 37, and closer to 35 because chlorine-35 is more common.
Isotopes: same protons, different neutrons.
Relative atomic mass: an average that accounts for abundance.
Calculate: multiply, add, divide by 100.
Spot the difference. Find the average.
Use the information in each diagram.
One point for each answer you get right first time.
No timer. Take your time and use a clue whenever you need one.