Formula mass and molar mass are the same. Atomic mass refers to atomic particles. When we write "formula mass", we usually mean the mass associated with 1 mole of such a formula; i.e. Avogadro's number of such a formula. Molar mass is the same thing: Avogadro's number of whatever stuff you have. The ability to successfully calculate equivalent masses of compounds is vital to success in At what weight percent is this? Consider a sample containing 100 atoms. For example, a sample of Fe-25at%C would contain 25 Carbon atoms and 75 Iron atoms. Weight of 25 C atoms = 25 x atomic weight of C / Avogadro's Constant = 4.98 atomic mass units. Weight of 75 Fe atoms = 75 x atomic weight of Fe / Avogadro's Constant = 69.74 atomic mass units Answers. The atomic weight is an average of an element’s atomic masses, weighted by the natural abundance of each isotope of that element. It is a weighted average because different isotopes have different masses. An atomic mass unit is 1/12th of the mass of a 12 C atom. The atomic mass or atomic weight is the decimal number, The number of significant figures varies according to the table, but the value is around 12.01. This value on a periodic table is given in atomic mass units or amu , but for chemistry calculations, you usually write atomic mass in terms of grams per mole or g/mol. 상대 원자 질량 (相對原子質量, 영어: relative atomic mass) 또는 원자량 (原子量, 영어: atomic weight )은 특정 환경 하에서 해당 원소의 동위 원소 의 존재 비율에 따라 가중평균한 질량 을 말한다. 주기율표 에는 지구 지각 이나 지구 대기권 을 기준으로 한 값을 말한다. Example: Calculating the atomic mass of a given chlorine sample where two isotopes are mixed. The first isotope has an atomic mass of 34.96885 and has an abundance of 75.78%. The second isotope has an atomic mass of 36.96590 and has an abundance of 24.22%. Step 1: (Atomic mass of each isotope) x (%Abundance /100) 34.96885*0.7578 = 26.50 (i) 36. One mole (abbreviated mol) is equal to 6.022×10 23 molecular entities (Avogadro’s number), and each element has a different molar mass depending on the weight of 6.022×10 23 of its atoms (1 mole). The molar mass of any element can be determined by finding the atomic mass of the element on the periodic table. The name derives from the Greek word beryllos for "beryl", a gemstone in which it is found (3BeO×Al 2 O 3 ×6SiO 2 ). Beryllium was discovered by the French chemist and pharmacist Nicholas-Louis Vauquelin in beryl and emerald in 1797. The element was first separated in 1828 by the French chemist Antoine-Alexandre-Brutus Bussy and independently GSPzvQx.