Particles > Structure, properties and function of elements (periodic table) > Properties and categorization of elements, the periodic table
The number of protons found in their nuclei identifies elements. There is a finite number of elements in nature which are all present in the periodic table. Most elements are natural but some are man made. All of these elements are arrange in a table, called the Periodic Table. They are ordered based on atomic number (number of protons), electron configuration, and recurring chemical properties.
Connection to Big Idea about energy: In the periodic table, a group is a vertical column. Elements in the same group show patterns in atomic radius and ionization energy. From top to bottom in a group, the atomic radii of the elements increase. Since there are more filled energy levels, valence electrons are found farther from the nucleus. From the top, each successive element has a lower ionization energy because it is easier to remove an electron since the atoms are less tightly bound.
Connection to Big Idea about forces: Electrons in the closer orbitals experience greater forces of electrostatic attraction; thus, their removal requires increasingly more energy. Ionization energy becomes greater up and to the right of the periodic table.
Connection to Big Idea about quantum: With the development of modern quantum mechanical theories of electron configurations within atoms, it became apparent that each period (row) in the table corresponded to the filling of a quantum shell of electrons.
Subjects related: Chemistry
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