The atomic number of an element is determined by the number of protons in it, and it is used to differentiate one element from another. The mass number of an element is determined by the number of protons and neutrons combined .
What is atomic number and mass number explain with example?
(i) Atomic number: The atomic number is the total number of protons present in the atom . For example, the atomic number of Mg is 12. ... For example, the atomic number of Lithium is 4 which is equal to the number of protons, the number of neutrons of magnesium is 4. The mass number is equal to 8(4+4).
What is the atomic number?
The atomic number is the number of protons in the nucleus of an atom . ... The number of protons determines how many electrons surround the nucleus, and it is the arrangement of these electrons that determines most of the chemical behavior of an element.
What are the atomic number and mass number of this atom?
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.
What is atomic mass and mass number?
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 .
Can 2 different elements have the same atomic number?
If two atoms have different numbers of protons, they are different elements. ... Two atoms with the same atomic number, but different mass numbers (same number of protons, different number of neutrons), are called isotopes , or isotopic nuclides.
Is atomic number and mass number the same?
An element’s mass number (A) is the sum of the number of protons and the number of neutrons. ... Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.
What is the example of mass number?
The mass number is commonly cited in distinguishing among the isotopes of an element , all of which have the same atomic number (number of protons) and are represented by the same literal symbol; for example, the two best known isotopes of uranium (those with mass numbers 235 and 238) are designated uranium-235 ( ...
What is an example of atomic mass?
An atomic mass unit is defined as a mass equal to one twelfth the mass of an atom of carbon-12 . The mass of any isotope of any element is expressed in relation to the carbon-12 standard. For example, one atom of helium-4 has a mass of 4.0026 amu. An atom of sulfur-32 has a mass of 31.972 amu.
What is atomic number and mass number Class 7?
Question 7
Mass number of an atom is the sum of the number of protons and neutrons in the nucleus of the atom. Mass number = Number of protons + Number of electrons. In the atom ‘B’, mass number = 35 and atomic number = 17. Number of protons = Atomic Number = 17 = p. Mass number = 17 + Number of neutrons.
What do you call the element from atomic number 57 71?
The elements from atomic number 57 to 71 are called Lanthanides . They are called lanthanides, since lanthanum is chemically identical to the elements in the sequence. ... The lanthanides are between Barium and Hafnium.
How do we find 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.
Is atomic mass a unit?
The atomic mass is useful in chemistry when it is paired with the mole concept: the atomic mass of an element, measured in amu , is the same as the mass in grams of one mole of an element. Thus, since the atomic mass of iron is 55.847 amu, one mole of iron atoms would weigh 55.847 grams.
What is nuclear mass?
[′nü·klē·ər ′mas] (nuclear physics) The mass of an atomic nucleus , which is usually measured in atomic mass units; it is less than the sum of the masses of its constituent protons and neutrons by the binding energy of the nucleus divided by the square of the speed of light.
What is atomic weight and atomic number?
Each atom, therefore, can be assigned both an atomic number (the number of protons equals the number of electrons) and an atomic weight ( approximately equaling the number of protons plus the number of neutrons ).
