Story of the atom Also known as the Atomic Timeline 440 BC th century

Democritus 440 BC Proposed the “atom” Atoms –are small, hard particles –constantly move –are “uncuttable” 440 BC th century

John Dalton 1803 Conducted experiments in combining elements All substances are made up of atoms Atoms of the same element are exactly alike Atoms of different elements are different Elements combine in specific proportions 440 BC th century

J. J. Thomson 1897 Conducted the cathode ray tube experiment There are small, negatively charged particles inside the atom “Plum pudding” model 440 BC th century

E. Rutherford 1911 Gold foil experiment Atoms contain mostly empty space Small, dense positively charged nucleus Most of the atom’s mass is in the nucleus Electrons move around in empty space in the atom 440 BC th century

N. Bohr 1913 Electrons travel in definite paths Electrons jump between levels from path to path 440 BC th century

Schrödinger and Heisenberg 20 th century Electron paths cannot be predicted Electrons are found in electron clouds, not paths 440 BC th century

Models of the atom….Pg.77 Essential Question: How has the model of the atom changed from ancient Greece till now? Solid Sphere (Dalton)  Plum pudding model (Thomson)  Rutherford (Empty space model)  Bohr (Electron shells)  Electron Cloud Model (Schrodinger and Heisenberg) Who first came up with the idea of the atom? Democritus What parts of Dalton’s theory of the atom are still true today? (Answer on page 73) 1.All elements are composed of atoms. 2.Atoms of the same element are similar and atoms of different elements are different. 3.Atoms of different elements can physically mix together (mixtures) or chemically combine (compounds). 4.Chemical reactions occur when atoms are separate, joined, rearranged.

Atomic Timeline page 78 Create a timeline to show the development of the atomic theory. Your timeline must include the following: 1. Name/year for each scientist. 1.The contribution of each scientist. 2.The model of the atom for each scientist.

Models of the atom ….Pg.79 Which models of the atom introduced the nucleus? Rutherford How does the electron cloud model differ from Bohr model? Electrons paths cannot be predicted in the electron cloud model, while in Bohr model electrons are found in specific orbits or shells and can jump from one shell to another.

Parts of the Atom---- pg.81 How big is an atom? Extremely small, under 1 nonometer( one billionth of a meter). Where are the subatomic particles located in an atom? Nucleus: Protons and neutrons. Electrons are outside of the nucleus.

Atomic number, Atomic mass and Isotopes----pg. 83 What is an isotope? Same element with a different number of neutrons. C-14 mass number What is the charge of the nucleus and why? Positive since it has contains the protons.

Review ElementCompound Two or more elements What is an element made up of?

Today we learned… That an element is made up of atoms Parts of an atom How the atom was discovered – atomic timeline

What is an atom? An atom is the ________ particle into which an element can be divided and still be the _________ substance. rkm.com.au

Atoms are building blocks of matter because… Atoms make up _______ Elements make up _________ Elements and compounds make up matter. element 1 element 2 Compound MATTER Atom 2 Atom 1

Parts of an atom Nucleus is the small, dense, _______________ of the atom. Protons ______charged particles in the nucleus. Neutrons are particles in the nucleus of an atom that have ________. Electrons are ________ charged particles found in electron ________ outside the nucleus.

Let’s compare the parts of the atom ChargeMassLocation ProtonPositive1 amuNucleus NeutronNo charge/ Neutral 1 amuNucleus ElectronNegativeAlmost zero Electron clouds (external to nucleus) 1 atomic mass unit (amu) = 1.7 X g

Properties of an atom Most of the atomic mass is present in the ________ because the mass of the electron is almost equal to zero. Mass of a proton = mass of a neutron= 1a.m.u The atom has no charge (neutral) because ______________ = ______________

There is something even smaller than protons and neutrons… _________ are smaller particles that make up protons and neutrons.

Which of these is NOT one of the basic pieces of an atom? 1.Electron 2.Proton 3.Quantron 4.Neutron

If I ask you to draw a nitrogen atom, what would you show in the nucleus of the atom? 1.Molecules 2.Neutrons 3.Protons 4.Electrons

How is the modern model of an atom different from the Bohr atomic model? 1.The masses of the atomic particles are different. 2.The numbers of electrons are different. 3.The shapes of the nuclei are different. 4.The arrangements of the electrons are different.

Wrapping up What we learned today –What is an atom? –Parts of an atom –Atomic timeline Homework –Timeline? Next time –Continue with more information about the atom –Learn about how atoms help elements find their spot on the Periodic Table I’m positive! I’m negative! I could care less!

Interactive periodic table:

Essential Question: pg. 87 How are the elements classified on the periodic table: Metals, non metals, and metalloids based on their properties.

Who was the first person to begin organizing the elements and what property did they use to do it? Dimitri Mendeleev. He used the increasing atomic mass based on repeating pattern of properties.

Where can you find the metals on the periodic table? They are found on the left of the zigzag line.

Your Question: How did Moseley organize the periodic table? He organized them by their atomic number and every element fell into proper place.

Essential Question (pg. 89): How are the elements classified on the periodic table? Metals, non metals, metalloids

What are the vertical columns of the periodic table called? Groups or families

What element is found in the third period of group 15? Phosphorus (P)

Your Question: what are the properties of Group 1 and 2? They are both very reactive.