Arrenite

Atoms and the periodic table

Ages 13 to 17 Read alone · about 50 minutes

Read together

Everything around you is made of atoms. An atom has a tiny nucleus of protons and neutrons, with electrons around it. The number of protons decides which element it is: hydrogen has 1, carbon has 6, oxygen has 8.

In 1869, the Russian chemist Dmitri Mendeleev arranged the known elements by weight and found that their properties repeated in a pattern. He even left gaps for elements not yet discovered, and predicted their properties. The periodic table is the descendant of that idea.

Elements in the same column behave alike. The metals on the left conduct electricity. The noble gases on the far right, such as helium and neon, rarely react.

Do it

  1. Print or draw a periodic table. Colour the metals, non-metals and noble gases in three different patterns, so it is clear without colour.
  2. Pick five elements (such as hydrogen, carbon, oxygen, iron, gold). Make a card for each with the symbol, number of protons, and one use.
  3. Draw a model of a carbon atom: 6 protons, 6 neutrons, 6 electrons. How do the electrons sit in shells (2, then 4)?
  4. Find the elements in a food label or a cleaning product. Which are you familiar with?

Talk about it

For the grown-up

The periodic table is a map of the building blocks of matter. Today it is arranged by proton number, an improvement made after Mendeleev. The 118 known elements include some made only in laboratories.

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Where this comes from
  • NGSS Lead States, Next Generation Science Standards: For States, By States (National Academies Press, 2013), performance expectation HS-PS1-1 (use the periodic table as a model to predict the relative properties of elements based on patterns of electrons in the outermost energy level)
  • International Union of Pure and Applied Chemistry (IUPAC), Periodic Table of the Elements
  • Eric R. Scerri, The Periodic Table: Its Story and Its Significance (Oxford University Press, 2007)

Written with AI assistance and checked against the sources listed. Please read it before sharing it with a child.