The Atom Grade 9 Science Ms. Raper.

What is an Atom??? The word atom comes from the Greek word Atmos which means unable to be divided. Democritus suggested that everything was made of tiny particles that could not be divided any further. We now know that atoms can be split into smaller pieces.

Different Models of the Atom John Dalton – the atom is like a billiard ball Thompson – The atom is like a chocolate chip cookie. Rutherford – the atom has a central nucleus with electrons around Bohr – positive nucleus and then empty space where the negative electrons orbit

What does and Atom look like? An atom has 2 main parts. A nucleus And orbits (shells)

The Nucleus Contains: Protons, these have a positive (+ve) charge Neutrons, these have zero (0) charge.

Orbits (shells) Orbiting the nucleus are negatively (-ve) charged particles called Electrons. These electrons are held in their orbits because they are attracted by the +ve protons

Atoms are different… Each element has its own unique number of Protons. This identifies which element is which Hydrogen has 1 proton Carbon has 6. This is called the atomic number (AN)

Each element has a place on the Periodic Table This place depends on how many PROTONS are found in the nucleus of the atom Protons give the atom MASS 1 proton has 1 mass weight.

Neutrons & Electrons Neutrons have no charge. They have a mass of 1 mass unit Electrons have a –ve charge. 2000 electrons weight the same as 1 proton Proton Neutron Electron Mass 1 1/2000 Charge +ve -ve

Atomic Number = Number of Protons Atomic Mass = Number of protons and the number of neutrons

Orbit Proton Nucleus Neutron Electron

Electron Arrangement The orbits can only hold a certain number of electrons. The first orbit closest to the nucleus can hold only 2 electrons The second orbit can hold 8 electrons The third orbit can hold 8 electrons

Number of electrons in Each Orbit. 1 2 3 4 Total # of electrons able to fit in the orbit 8 18

Rules Atomic Number = 10 Atomic Mass = 20 Electrons = 10 2,8,0,0 The orbits must be filled in order. First the orbit closest to the nucleus and then the next. And so on Atomic Number = 10 Atomic Mass = 20 Electrons = 10 2,8,0,0 Element = ?

= # of protons & neutrons Element # Name Symbol Atomic Mass Number = # of protons & neutrons Atomic Number = # of protons Number of neutrons = AMN - AN Number of Electron = number of protons Electron Arrangement 1 Hydrogen H 1,0,0,0 2 Helium He 4 2,0,0,0 3 Lithium Li 6 2,1,0,0 Beryllium Be 9 5 2,2,0,0 Boron B 10 2,3,0,0 Carbon C 12 2,4,0,0 7 Nitrogen N 14 2,5,0,0 8 Oxygen O 16 2,6,0,0 Fluorine F 19 2,7,0,0 Neon Ne 20 2,8,0,0 11 Sodium Na 22 2,8,1,0

= # of protons & neutrons Element # Name Symbol Atomic Mass Number = # of protons & neutrons Atomic Number = # of protons Number of neutrons = AMN - AN Number of Electron = number of protons Electron Arrangement 12 Magnesium Mg 24 2,8,2,0 13 Aluminum Al 26 2,8,3,0 14 Silicon Si 28 2,8,4,0 15 Phosphorus P 30 2,8,5,0 16 Sulfur S 32 2,8,6,0, 17 Chlorine Cl 35 18 2,8,7,0 Argon Ar 39 20 2,8,8,0 19 Potassium K 2,8,8,1 Calcium Ca 40 2,8,8,2

What are these 3 Elements?

What are these 3 Elements?

P= N=