Atoms, Elements & the Periodic Table
Concept 3: Atoms, Elements & the Periodic Table
Success Criteria & Vocabulary
Click this drop-down menu to see the Success Criteria.
I can describe an atom and its basic structure.
I can state the mass and charge carried by protons, neutrons, and electrons.
I can define what an element is.
I can recognise the periodic table and why it is important.
I can recall the names of the first 20 elements.
I can determine the number of protons, neutrons, and electrons for an element.
Click this drop-down menu to see the list of Vocabulary.
Atom: Smallest unit of matter - all matter is made of this.
Atomic number: Number of protons in an atom.
Electron: Subatomic particle that is negatively charged and has a mass of 1/1840
Element: Substance that consists of only one type of atom.
Group: Vertical columns of the periodic table.
Mass number: Total number of protons and neutrons in an atom.
Neutron: Subatomic particle that has no charge and has a mass of 1.
Period: Horizontal rows of the periodic table.
Periodic table: Chart that arranges all known elements according to their properties.
Proton: Subatomic particle that is positively charged and has a mass of 1.
Getting to Know the First 20 Elements
Extra Task for Experts: PhET Simulation
I recommend that you choose one of the games. For this task, you must remember that atoms are neutral (no overall charge). Once an atom has a charge (+ve or -ve), it is now called an ion.
An ion is positively charged if there are more protons than electrons.
An ion is negatively charged if there are more electrons than protons.
Learn the 10 keywords using Quizlet:
Concept 3: Support Notes
Everything is made from ATOMS, including you. Atoms are tiny particles that are far too small to see, even with a microscope. If people were the same size as atoms, the entire population of the world could stand on the tip of a pin!
ATOMS are made up of 3 main types of particles: ELECTRONS, PROTONS, and NEUTRONS. Each of these particles have different properties.
Electrons are tiny particles that have a negative electrical charge (-). They surround the centre (nucleus) of the atom.
Protons are much larger and heavier than electrons and have the opposite charge. They have a positive electrical charge (+).
Neutrons are large and have a similar mass to protons. Neutrons have no electrical charge (0).
The nucleus is at the centre of the atom and contains the protons and neutrons. Pretty much all the mass of the atom is concentrated at the nucleus, because the electrons have very little mass.
Above: Bohr model of an atom.
Right: Excellent summary table of the 3 subatomic particles, in terms of their symbol, mass, charge, and location.
Elements are everywhere.
Scientists have found more than 130 types of atoms. ELEMENTS are pure substances made up of only one type of ATOM. Each element has its own name. For example, carbon, oxygen, and gold are all elements.
Over 130 elements make up all matter in the universe, but only about 20 elements are commonly found on Earth. Each type of element has a unique type of atom/particle (being the only one of its kind). The Earth, as well as all living things on it is made up of a combination of elements in different forms.
Many of the common types of elements are grouped in the first 20 elements out of 130+ elements. These elements can either be gas, liquid, or solid at room temperature.
The atoms of some elements do not join together, but instead stay as separate atoms. Helium is like this.
On the other hand, atoms of other elements, such as hydrogen and oxygen, join together to make molecules.
(Molecule = A collection of two or more atoms held together by chemical bonds).
Pictured below: First 20 elements, in their pure form.
Other elements that are common can be found further down the list of elements. Many of these common elements tend to be metals.
Each element is named and has its own symbol.
ELEMENTS consist of only one type of ATOM. Each element can be represented by its own special chemical symbol, which is made up of one or two letters.
The element symbols are one or two letters, formed from the name of the element. Such as H for hydrogen, or He for helium. The first letter of the symbol is always a capital letter. Any other letters are lower case. E.g. helium is He, not HE or he.
If the symbols are not based on an element's English name, then it is most likely to be based on its Latin name, the original language of Science. Some elements have a symbol based on their old Latin name, even though the name of the element has now changed to a more English one.
For example, if someone asked you to guess the chemical symbol for sodium, you would probably say 'S' or 'So'. However, sodium's Latin name is 'natrium'. The chemical symbol for sodium is 'Na' and comes from its Latin name.
Featured Element: Carbon
Carbon is one of the most important ELEMENTS for living organisms, and it is also present in many non-living substances as well as many fuels, types of rocks, and as part of carbon dioxide in the air.
There is a fixed amount of carbon on Earth, and it gets recycled from living organisms when they die by decomposers in the soil, and is added to the atmosphere as carbon dioxide when they respire. Some susbtances are pure carbon, such as diamonds, coal, and graphite.
Featured Element: Oxygen
Oxygen is essential for living organisms and is required to break down the food into energy during respiration. Pure oxygen is found as a gas on Earth.
Most of our oxygen in the atmosphere came from organisms - bacteria at first, then plankton and plants, which broke apart water and released the oxygen during photosynthesis.
Oxygen is a very reactive gas and causes many metals to corrode and rust, chemically combining with the metal to form a compound.
Featured Element: Hydrogen
Hydrogen is the most common ELEMENT in the universe, and is the main component (ingredient) in stars, including our Sun. Nuclear reactions inside the Sun and stars change the hydrogen in to helium, another common element, and release large amounts of energy. Life on Earth is dependent on this energy source and planets too far away are too cold for living organisms to survive.
Hydrogen was also used for bombs that were far more destructive than traditional chemical weapons.
Hydrogen is now being extracted from water and used as a form of fuel.
The Periodic Table of Elements
All the different elements are arranged in a chart called the PERIODIC TABLE. A Russian scientist called Dmitri Mendeleev created a periodic table in the 19th century and placed the ELEMENTS in groups based on the element's similar properties. Not all the elements had been discovered at the time he had created the table, so he left gaps that have now mostly been filled.
The modern periodic table is based closely on the ideas that Mendeleev used:
The elements are arranged in order of increasing number of protons (also known as ATOMIC NUMBER).
The horizontal rows are called PERIODS.
The vertical columns are called GROUPS.
Elements in the same group are similar to each other.
Study the periodic table below. I specifically chose this periodic table, because it focuses you on:
The first 20 elements, plus the most common elements past the first 20.
Which elements are solids, liquids, and gases.
Which elements are metals and non-metals (next topic).
Elements in the right-most column are highly reactive. Elements in the left-most column are unreactive.
You must learn the names of the first 20 elements + 8 common elements in the periodic table.
What Makes Each Element Different?
Each ELEMENT has a unique ATOMIC NUMBER and MASS NUMBER. Using these numbers, you can work out the number of protons, neutrons, and electrons.
Number of protons = atomic number (the small number)
Number of electrons = same as the number of protons
Number of neutrons = mass number (the big number) - number of protons