Introduction to the periodic table - Introduction to Chemistry

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Introduction to the periodic table


• The periodic table is an organized list of all the different types of atoms known to scientists.

• We call each different type of atom an element. Whenever you read 'element' in chemistry, the reading is talking about a unique type of atom.

• The difference between elements (that defines an element) is the number of protons that an atom of that element contains. For example, carbon atoms by definition always have 6 protons contained in them. If an atom doesn’t have 6 protons, it isn’t a carbon atom.

• The periodic table arranges all known elements by the number of protons they contain. This is known as their atomic number or their proton number.

• More generally, the periodic table is arranged in groups which run vertically (up and down), and periods which run horizontally (across). For example, all of the elements in the first column on the left of the table are called group 1 elements.

• For each element, the entry in the periodic table displays its chemical symbol, its atomic mass (or its mass number), the larger number, and its atomic number (or proton number) which is the smaller number.

• A proton is a particle contained within the atom that affects the properties of elements. We'll learn more about the proton in a later lesson!

In this lesson, we will learn:
• What information the Periodic Table tells us.
• The definition of element, proton number and mass number.
• The arrangement of the Periodic Table.
• The fundamental particle the Periodic Table is based on.
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Introduction to the periodic table

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