2.4 Structure of the Atom Science 8 Name:________________ Date:_________________ Block:____

An atom is made up of electrons, neutrons, and protons. Atom: the smallest particle of an element that retains the properties of that element All matter is made up of atoms Atoms are made up of subatomic particles atom: the smallest particle of an element that retains the properties of that element

Structure of the Atom What do you remember about the structure of the atom? List at least 4 points __________________________________________

The Atom: Nucleus Nucleus Tiny region at the centre of the atom The nucleus makes up almost 100% of the mass of the atom. Most hydrogen atoms: contain one proton All other atoms: contain both protons and neutrons Number of protons determines charge of the nucleus and the identity of an atom

The Atom: Electron Energy Shell The region that electrons occupy accounts for over 99.99% of an atom’s volume Electrons occupy specific regions (energy levels) that surround the nucleus Electrons are like a spread- out cloud of negative charge that exists in the whole region at once Electrons can jump to higher energy levels by absorbing energy or lower energy levels by losing energy

Electrons Electrons jumping to higher Energy absorbed Energy Released Electrons jumping to higher energy level, by absorbing energy Electrons jumping to a lower energy level and releases energy

The Atom: Electric Charge Comes in two types: positive and negative Protons: positive charge (1+ each) Electrons: negative charge (1– each) Neutrons: no charge Like charges REPEL one another. Provide an example. ++ , -- Opposite charges ATTRACT one another. Provide an example. +- The overall charge of an atom is 0 In an atom: the number of protons = the number of electrons

The Nucleus: Electric Charge What subatomic particles are found inside the nucleus? Proton and neutrons Protons have a positive charge Neutrons have no charge We just learned that like charges REPEL one another Yet the nucleus has not explode. Why? There is a STRONG FORCE also known as NUCLEAR FORCE that holds the nucleus together This force is very strong across very short distances It counteracts the repulsion between protons so that the protons in the nucleus does not fly apart. Neutrons between the protons also help stabilize the nucleus.

Protons and Neutrons are made of elementary particles Protons and Neutrons are made up of elementary particles called quarks The quarks are bonded together by gluons (kind of like glue) 2 up quarks 1 down quark gluon

Periodic Table Song: https://www.youtube.com/watch?v=VgVQKCcfwnU The Periodic Table

Origin of the Periodic Table There are many different elements that exist on earth. Chemists wanted to find a way to organize and group all the different elements on earth In 1867, Dimitri Mendeleev found patterns in the elements and organized them into a table. He organized elements based on their atomic number (the number of protons) Elements are characterized by their atomic number This became known as the periodic table The resulting table had a few empty spots. These “empty spots” are elements that have not been discovered yet.

Origin of the Periodic Table Take a look at your periodic table Do you see a pattern based on atomic number?

Periodic Table Name – Titanium Symbol – Ti 4 Periodic Table 5 2 1 3 Name – Titanium Symbol – Ti Average Atomic Mass – mass of the AVERAGE atom – 47.9 Atomic number – number of protons – 22 (Notice how the pattern increases one by one throughout the periodic table) Ion Charges – 4+, 3+

Practice What is the overall charge of an atom? What relationship do the number of protons and the number of electrons have in an atom? An atom is neutral The number of protons = the number of electrons

Practice K B Name Atomic number Average Atomic mass Number of protons   Name Atomic number Average Atomic mass Number of protons Number of electrons 19 K Potassium 39.1 5 B Boron 10.8 Potassium Boron 19 5 39.1 10.8 19 5 19 5