Difference Between Atomic Weight and Atomic Mass

Difference Between Atomic Weight and Atomic Mass Atomic weight and atomic mass are two important concepts in chemistry and physics. Many people use the terms interchangeably, but they dont actually mean the same thing. Take a look at the difference between atomic weight and atomic mass and understand why most people are confused or dont care about the distinction. (If youre taking a chemistry class, it could show up on a test, so pay attention!) Atomic Mass Versus Atomic Weight Uranium has two primordial isotopes (uranium-238 and uranium-235). Uranium-238 has 92 protons plus 146 neutrons and uranium-235 92 protons and 143 neutrons. Â  Pallava Bagla/Getty Images Atomic mass (ma) is the mass of an atom. A single atom has a set number of protons and neutrons, so the mass is unequivocal (wont change) and is the sum of the number of protons and neutrons in the atom. Electrons contribute so little mass that they arent counted. Atomic weight is a weighted average of the mass of all the atoms of an element, based on the abundance of isotopes. The atomic weight can change because it depends on our understanding of how much of each isotope of an element exists. Both atomic mass and atomic weight rely on the atomic mass unit (amu), which is 1/12th the mass of an atom of carbon-12 in its ​ground state. Can Atomic Mass and Atomic Weight Ever Be the Same? If you find an element that exists as only one isotope, then the atomic mass and the atomic weight will be the same. Atomic mass and atomic weight may equal each other whenever you are working with a single isotope of an element, too. In this case, you use the atomic mass in calculations rather than the atomic weight of the element from the periodic table. Weight Versus Mass: Atoms and More Mass is a measure of the quantity of a substance, while weight is a measure of how a mass acts in a gravitational field. On Earth, where we are exposed to a fairly constant acceleration due to gravity, we dont pay much attention to the difference between the terms. After all, our definitions of mass were pretty much made with Earth gravity in mind, so if you say a weight has a mass of 1 kilogram and a 1 weight of 1 kilogram, youre right. Now, if you take that 1 kg mass to the Moon, its weight will be less. So, when the term atomic weight was coined back in 1808, isotopes were unknown and Earth gravity was the norm. The difference between atomic weight and atomic mass became known when F.W. Aston, the inventor of the mass spectrometer (1927) used his new device to study neon. At that time, the atomic weight of neon was believed to be 20.2 amu, yet Aston observed two peaks in the mass spectrum of neon, at relative masses 20.0 amu and 22.0 amu. Aston suggested there two actually two types of neon atoms in his sample: 90% of the atoms having a mass of 20 amu and 10% with a mass of 22 amu. This ratio gave a weighted average mass of 20.2 amu. He called the different forms of the neon atoms isotopes. Frederick Soddy had proposed the term isotopes in 1911 to describe atoms that occupy the same position in the periodic table, yet are different. Even though atomic weight is not a good description, the phrase has stuck around for historical reasons. The correct term today is relative atomic mass - the only weight part of the atomic weight is that it is based on a weighted average of isotope abundance.

Great Love Quotes That Will Evoke the Flame of Love

Great Love Quotes That Will Evoke the Flame of Love Great is what great does. Great love quotes are no exception to this rule. These love quotes have become great because they have infused and inspired the feelings of love in many a soul. A few of these great love quotes are sure to stir up love and romantic feelings in your heart too. Love is the strange bewilderment, which overtakes one person on account of another person. James Thurber and E. B. White The best and most beautiful things in this world cannot be seen or even heard, but must be felt with the heart. Helen Keller The most difficult thing to explain in life is the simplest truth called love. Ramanathan Srinivasan A dream you dream alone is only a dream. A dream you dream together is reality. John Lennon Its a very dangerous state. You are inclined to recklessness and kind of tune out the rest of your life and everything thats been important to you. Its actually not all that pleasurable. I dont know who the hell wants to get in a situation where you cant bear an hour without somebodys company. Colin Firth As we have explained, in first love the soul is taken long before the body; later the body is taken long before the soul; sometimes the soul is not taken at all. Victor Hugo As soon go kindle fire with snow, as seek to quench the fire of love with words. William Shakespeare Love cannot endure indifference. It needs to be wanted. Like a lamp, it needs to be fed out of the oil of anothers heart, or its flame burns low. Henry Ward Beecher Love is when you look into someones eyes and go all the way inside; to their soul and you both know... instantly! Angela Chase Find the person who will love you because of your differences and not in spite of them and you have found a lover for life. Leo Buscaglia With love one can live even without happiness. Fyodor Dostoyevsky Love is a better teacher than duty. Albert Einstein The prerequisite for making love is to like someone enormously. Helen Gurley Brown To love is nothing. To be loved is something. But to love and be loved, thats everything! T. Tolis True love stories never have endings. Richard Bach A woman knows the face of the man she loves as a sailor knows the open sea. Honore de Balzac In real love you want the other persons good. In romantic love you want the other person. Margaret Anderson Youll discover that real love is millions of miles past falling in love with anyone or anything. When you make that one effort to feel compassion instead of blame or self-blame, the heart opens again and continues opening. Sara Paddison Love is like war: easy to begin but very hard to stop. H. L. Mencken True love is when your heart and your minds are saying the same thing. Leanna L. Bartram I have found the paradox that if you love until it hurts, there can be no more hurt, only more love. Mother Teresa Truly loving another means letting go of all expectations. It means full acceptance, even celebration of anothers personhood. Karen Casey Love is a friendship set to music. Joseph Campbell Blessed is the season, which engages the whole world in a conspiracy of love. Hamilton Wright Mabie I think what motivates people is not great hate, but great love for other people. Huey Newton Life without love is like a tree without blossoms or fruit. Khalil Gibran Love takes off masks that we fear we cannot live without and know we cannot live within. James Baldwin Love is a gift, not an obligation, follow your heart and always trust the person you love. Anonymous Love does not begin and end the way we seem to think it does. Love is a battle, love is a war; love is a growing up. James A. Baldwin Honesty is the only way with anyone, when youll be so close as to be living inside each others skins. Lois McMaster Bujold Love is something eternal†¦ The aspect may change, but not the essence. Vincent Van Gogh Love is a smoke made with the fume of sighs. William Shakespeare Whats meant to be will always find a way. Trisha Yearwood To be able to say how much you love is to love but little. Petrarch The best proof of love is trust. Joyce Brothers Whoso loves, believes the impossible. Elizabeth Barret Browning