10 Questions
What defines an element and can be used to automatically know the number of protons in an atom of that element?
Atomic number
Which property is not a fundamental property of a given element?
Mass number
What must be known to find the mass number of a given atom?
Number of neutrons
What is the weighted average of mass numbers of all atoms of an element?
Atomic mass
What is the atomic number of an atom?
The number of protons it has
What is the mass number of a given atom?
The number of protons and neutrons it contains in its nucleus
Which subatomic particle has a positive charge and is located in the nucleus of an atom?
Proton
What is the mass of an electron?
0 amu
Which subatomic particle determines the atomic number of an element?
Proton
What are atoms with the same atomic number but different mass numbers called?
Isotopes
Study Notes
- Atoms have subatomic particles called electrons, protons, and neutrons.
- Electrons travel in orbitals outside the nucleus, have no charge and a mass of approximately 1 atomic mass unit (amu).
- Protons are positive charged particles with a mass of 1 amu, reside in the nucleus, and determine the atomic number of an element.
- Neutrons are neutral particles, with a mass of 1 amu, present in the nucleus, and do not influence the atomic number.
- An atom's atomic number can be found on the periodic table and indicates the number of protons in the nucleus.
- The mass number of an atom is the sum of protons and neutrons in its nucleus and determines the total number of nucleons in the nucleus.
- Atoms with the same atomic number but different mass numbers are called isotopes.
- The mass number and atomic number can be represented together as the mass number (superscript) followed by the atomic number (subscript) to the left of the element symbol.
- The number of neutrons in an atom can be calculated by subtracting the atomic number from the mass number.
- The atomic number and mass number provide essential information about an element and its isotopes.
Learn about the concepts of atomic number and mass number, which are fundamental in understanding the structure of atoms. Atomic number is determined by the number of protons, while mass number is the sum of protons and neutrons in an atom.
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