Periodic Table 2025

SEM 1 Science Exam Revision

What is the periodic table

a table of chemical elements arranged by atomic number

how to find the number of protons in an element

the number of protons in an element is the atomic number

how to find the number of electrons in an element

the number of electrons in an element is the atomic number

how to find the number of neutrons in an element

the number of neutrons in an element is the atomic number subtracted from the mass number.

properties of metals

high melting points, shiny, malleable, ductile, and good conductors of heat and electricity

properties of non-metals

low melting points, dull, brittle, and poor conductors of heat and electricty

properties of ionic bonds

high melting and boiling points, brittleness, strong electrostatic forces and able to dissolve in water.

properties of covalent bonds

low melting and boiling points, poor electrical conductivity, and soluble in solvents (not water)