Relative isotopic masses are always close to whole-number values , but never (except in the case of carbon-12) exactly a whole number, for two reasons: protons and neutrons have different masses, and different nuclides have different ratios of protons and neutrons.
Why is mass number always a whole number quizlet?
Is the mass number a whole number? Yes, it is a whole number because it is the sum of the number of protons and neutrons in an atom .
Why is the mass number of an isotope always a whole number?
It is also called atomic mass number or nucleon number. Different isotopes of the same element have different mass numbers because their nuclei contain different numbers of neutrons. ... The mass number is always a whole number; because it is a count of the particles .
Why is mass number always a whole number but atomic mass fractional?
Now since there can't be a fraction of either one of them in any atom, the mass number is a whole number. But due to existence of isotopes there are two different atoms of same element with different mass number by same atomic numbers . ... Hence Atomic can be fractional but Mass number is always a whole number.
Why is the mass number not a whole number?
The mass number is always a whole number; because it is a count of the particles . It differs from the exact mass of the atom in atomic mass units, amu, which is often known and expressed to six decimal places.
Why is Oxygen's atomic mass not a whole number?
The actual masses of individual oxygen atoms are not whole numbers even though their mass numbers are whole numbers. When protons and neutrons combine to form the oxygen nucleus, a very small amount of the total mass is converted to nuclear binding energy. ... It must be experimentally determined using a mass spectrometer.
What is a rule for determining mass?
The number of protons, neutrons, and electrons in an atom can be determined from a set of simple rules. The number of protons in the nucleus of the atom is equal to the atomic number (Z). ... The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus .
What is a rule for determining the mass quizlet?
what is a rule for determining the mass number of an atom or ion. mass number=protons + neutrons . which particles affect the stability of the atom . protons and neutrons . which particles don't affect the stability of the atom.
Is the atomic weight a whole number quizlet?
Yes, it is a whole number because it is the sum of the number of protons and neutrons in an atom.
Are atomic numbers always whole?
The atomic number is simply the number of protons in an atom. For this reason, it's sometimes called the proton number. ... Because protons are units of matter, atomic numbers are always whole numbers . At present, they range from 1 (the atomic number of hydrogen) to 118 (the number of the heaviest known element).
Is atomic mass and mass number the same?
Atomic mass is also known as atomic weight. Atomic mass is the weighted average mass of an atom of an element based on the relative natural abundance of that element's isotopes. The mass number is a count of the total number of protons and neutrons in an atom's nucleus.
What is the appropriate mass of one proton?
Proton, stable subatomic particle that has a positive charge equal in magnitude to a unit of electron charge and a rest mass of 1.67262 × 10 − 27 kg , which is 1,836 times the mass of an electron.
How do you find the mass number?
Together, the number of protons and the number of neutrons determine an element's mass number: mass number = protons + neutrons . If you want to calculate how many neutrons an atom has, you can simply subtract the number of protons, or atomic number, from the mass number.
How do we calculate atomic mass?
For any given isotope, the sum of the numbers of protons and neutrons in the nucleus is called the mass number. This is because each proton and each neutron weigh one atomic mass unit (amu). By adding together the number of protons and neutrons and multiplying by 1 amu , you can calculate the mass of the atom.
What does mass number represent in an isotope?
The mass number of an isotope is the total number of protons and neutrons in an atomic nucleus . If you know that a nucleus has 6 protons and 6 neutrons, then its mass number is 12.
Why is oxygen mass less than 16?
However, average atomic mass is listed as less than 16 — this is because there are also radioisotopes of oxygen — meaning that there are isotopes of oxygen that are radioactive . There are 9 of these, going up to an atomic mass of 24 (which means the oxygen has 8 protons and 16 neutrons!)
