Atoms and the Periodic Table. What is an atom? The Basic Building Block of matter.

Atoms and the Periodic Table

What is an atom?

The Basic Building Block of matter.

What are the three parts that it is made of?

Protons Neutrons Electrons

What are Protons? Positively Charged Particles Found in the nucleus of an atom.They are about the same mass as a

neutron.

What are neutrons?Neutral particles or parts of an atom

with NO CHARGE.They are found in the nucleus of an

atom. A neutron is about the same mass as a

proton.

What are electrons? Negatively charged particles They are found floating around the

nucleus.Electrons are very small

Protons are about 1,836 times more mass than an electron.

What is an element?

A type of atom with a specific number of PROTONS.

What is the periodic table of elements?

The periodic table is a table that tells us the atomic number, the atomic mass and the chemical symbol of an element. It shows trends in properties of the

elemental groups.

What is a chemical symbol?

A short way of writing a the name of a Chemical. For example: Boron has a chemical

symbol “B”.

What is an atomic number?

The atomic number is the number at the top of the box, which identifies how many protons are in an element. Every element has a unique atomic

number.

What is atomic mass?

Atomic mass is the number of neutrons + the number of protons in the nucleus of the atom.

Atomic mass can be found at the bottom of the element’s box.

How do you use the atomic mass number and the atomic number to find the neutrons in

an element? The atomic mass – the atomic

number = the number of neutrons

Atomic Theory

Ancient Greeks

Atomic theory according to Dalton

All elements are composed of atoms that cannot be divided.

All atoms of the same element are exactly alike and have the same mass. Atoms of different elements have different masses.

Atomic theory according to Dalton

Atoms of one element cannot be changed into atoms of a different element.

Every compound is composed of atoms of different elements, combined in a specific ratio.

Advancements

Thomson- Postive and negative charges of atom.

Rutherford- The Nucleus contains protons.

Bohr- Electrons have a certain quantity of energy.

Advancements

Cloud model- Electrons don’t circle the nucleus like planets, they are in cloud like regions.

Chadwick – He discovered neutrons in the nucleus.

Modern atomic theoryAt the center of an atom there is a tiny

massive nucleus containing protons and neutrons. Surrounding the nucleus is a cloudlike region of moving electrons.

Number of protons neutrons and electrons

Atomic number = the number of protonsAtomic mass = the number of protons

and neutronsThe number of electrons is equal to the

number of protons.

Isotopes

Isotope= atoms of the same element that have a different number of neutrons.

Remember, the number of protons is always the same.

Periodic table of elements

The periodic table is an arrangement of elements showing the repeating pattern of their properties.

The periodic table can be used as a tool to predict the properties of an element.

Periodic table of elements