ELEMENTS AND ATOMS NOTES

Matter and Atoms  Matter is anything that takes up space and has mass  There are 4 phases of matter solid, liquid, gas, and plasma.  All matter is made of atoms.  Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses.

The Atomic Model  An atom has three parts.  Protons are positive and in the nucleus of the atom.  Neutrons have a neutral charge and are also found in the nucleus.  Electrons have a negative charge and they orbit the atom in what is known as an electron cloud.  Brain Pop Atoms MovieAtoms Movie

John Dalton-The Atomic Man  John Dalton was an English chemist.  He came up with the many of the ideas that we still utilize today about atoms and the way they are represented.  Through his research Dalton developed 5 postulates or things he believed about atoms.

Dalton’s Postulates 1. Every element is composed of tiny particles. 2. These particles are called atoms. 3. All atoms of a given element are identical, atoms of different elements have different properties. 4. Atoms of an element are NOT changed into atoms of another element through chemical processes. Matter can not be created nor destroyed. 5. Compounds are formed when atoms of more than one element combine.

Dalton’s Laws  Law of Constant Composition is that “any given compound always consists of the same atoms and the same ratio of atoms.  For example, water always consists of oxygen and hydrogen atoms, and it is always 89% oxygen by mass and 11% hydrogen by mass.

Dalton’s Laws  Law of Conservation of Mass is that the total mass of materials before and after a chemical reaction must be the same.  Matter can not be created or destroyed during a chemical reaction.  The mass of the reactants should be equal to the mass of the products.

Elements  Elements are the alphabet to the language of molecules.  To make molecules, you must have elements.  Elements are made of atoms. While the atoms may have different weights and organization they are all built the same way.  Elements can not be broken down into smaller substances by chemical or physical means.  Elements contain one type of atom(s).  Element Song Element Song

Naming the Elements  The first 103 elements have internationally accepted names, which are derived from:  The compound or substance in which the element was discovered.  An unusual or identifying property of the element.  Places, cities, and countries.  Famous scientists.  Greek Mythology  Astronomical objects.

Different types and versions of atoms

More Information about Elements  Elements are the building blocks of all matter.  The periodic table is a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry.  The periodic table tells us several things…

Periodic Table Basics 8 O Oxygen 16 Atomic Number: Number of protons and it is also the number of electrons in an atom of an element. Element’s Symbol: An abbreviation for the element. Elements Name Atomic Mass/Weight: Number of protons + neutrons.

Atomic Mass= (#P) + (#N)  Atomic Number tells how many protons  For every proton (+) there is an electron (-)  Atomic mass number tells haw many P and N number tells haw many P and N

Practice  Open your books to page L*169 and use the periodic table for the practice elements. Fluorine  Symbol=  Atomic #=  Atomic Mass=  # P=  #E=  #N=

Practice Zinc Symbol= Atomic #= Atomic Mass= # P= #E= #N= Boron Symbol= Atomic #= Atomic Mass= # P= #E= #N=

Structure of an Atom  Nucleus (protons and neutrons)  1 st shell =2 electrons  2 nd shell =8 electrons  3 rd shell =8 electrons  4 th shell =18 electrons

Electron Rules  You can’t just shove all of the electrons into the first orbit of an electron.  Electrons live in something called shells.  Only so many can be in any certain shell.  The electrons in the outer most shell of any element are called valence electrons

Different Atomic Models  There are two models of the atoms we will be using in class.  Bohr Model and the Lewis Dot Structure

The Bohr Model  The Bohr Model shows all of the particles in the atom.  In the center is circles. Each circle represents a single neutron or proton. Protons should have a plus or P written on them. Neutrons should be blank or have an N.  In a circle around the nucleus are the electrons. Electrons should have a minus sign or an e.

Let’s Draw LITHIUM!!!!!!!  How to draw a Lithium atom  First, look at the Periodic Table  Second, determine the number of protons the atomic number)  Then determine the number of neutrons (Atomic mass – atomic number)  Then determine the number of electrons the atomic number) 3 Li Lithium 7

The Lewis Dot Structure for Oxygen  The Lewis Dot Structure is a bit different from the Bohr model.  It only shows the element symbol and it’s outer most electron shell. O

Lewis Dot Structure for Lithium 1. Write the symbol. 2. Start on the right hand side, working your way clockwise around the symbol. 3. Try Lithium

Practice Now Draw the Atom in both Bohr and Lewis Dot Structure: Magnesium Symbol= Atomic #= Atomic Mass= # P= #E= #N=