Elements & The Periodic Table

The 2021 NCEA Level 1 Periodic Table shows the elements and their symbols of 118 elements. Scientists are continually discovering new elements so the number of elements known will increase over time. The Periodic Table also shows the atomic number of each element. On this particular Periodic Table the mass number (atomic mass or molar mass) of each element is not given.

The rows of the Periodic Table are called Periods, and the columns are called Groups. An element will generally have similar properties to other elements in the same group.

Elements are made up of only one type of atom. For example, the element magnesium is only made of magnesium atoms, the element oxygen is made up only of oxygen atoms. This means that atoms of a particular element contain the same number of protons.

Groups & Periods

As explained earlier the Periodic Table is organised into Groups and Periods.

Groups of the Periodic Table are the columns. All elements in the same group have similar properties. Elements of the same group also have the same number of valence (outer shell) electrons. Group 1 elements have 1 valence electron, Group 16 elements have 6 valence electrons, and so on. Although most Group 18 elements have 8 valence electrons, the element helium only has 2 electrons. Group 18 elements have a full valence shell of electrons.

Periods of the Periodic Table are the rows. All elements in the same period have the same number of energy levels or shells of electrons. Period 1 elements (hydrogen, H & helium, He) have just one energy level or shell of electrons. All Period 2 elements (lithium, Li, beryllium, Be; boron, B; carbon, C; nitrogen, N; oxygen, O; fluorine, F; & neon, Ne) have 2 energy levels or shells of electrons. All Period 3 elements have 3 energy levels or shells or electrons, and Period 4 elements have 4 energy levels or shells of electrons.

Video - Groups & Periods of The Periodic Table

Video - The Genius of Mendeleev's Periodic Table

Elements & Their Symbols

The Periodic Table Song

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