Nucleus and Electrons
Atoms consist of a central nucleus and surrounding electrons.
Electrons: Negative charge.
Nucleus: Contains protons (positive charge) and neutrons (neutral).
Atoms have no overall charge due to balance of protons and electrons.
Periodic Table: Lists elements with specific properties.
Each element’s symbol has two key numbers:
Atomic Number:
Represents the number of protons.
Example: Lithium has an atomic number of 3, meaning it has 3 protons and 3 electrons.
Mass Number:
Total of protons and neutrons in the nucleus.
Example: Lithium has a mass number of 7 (3 protons + 4 neutrons).
Calculation of Neutrons:
Neutrons = Mass Number - Atomic Number.
Boron:
Protons: 4, Neutrons: 5, Electrons: 4.
Sodium:
Protons: 11, Neutrons: 12, Electrons: 11.
Fluorine:
Protons: 9, Neutrons: 10, Electrons: 9.
Phosphorus:
Protons: 15, Neutrons: 16, Electrons: 15.
Definition: Isotopes are variants of the same element with different neutron counts.
Example: Lithium has isotopes.
Most isotopes of lithium: 3 protons, 4 neutrons.
Common Isotopes of Carbon:
Isotope 1: 6 protons, 6 neutrons.
Isotope 2: 6 protons, 7 neutrons.
Isotope 3: 6 protons, 8 neutrons.
Common isotopes of Chlorine:
Isotope 1: 17 protons, 18 neutrons.
Isotope 2: 17 protons, 20 neutrons.
Definition: Ions are atoms with an overall charge due to the loss or gain of electrons.
Positive ions (cations): Lost electrons.
Negative ions (anions): Gained electrons.
Examples:
Sodium Ion (Na+): 11 protons, 12 neutrons, 10 electrons (lost one electron).
Fluoride Ion (F-): 9 protons, 10 neutrons, 10 electrons (gained one electron).
Practice:
Oxide Ion (O^2-): 8 protons, 8 neutrons, 10 electrons (gained two electrons).
Aluminium Ion (Al^3+): 13 protons, 14 neutrons, 10 electrons (lost three electrons).
Additional resources available for further practice on atomic structure and ions.