Chemistry Periodic Table and Bohr-Rutherford Diagrams.

ChemistryPeriodic Table and Bohr-Rutherford Diagrams

Structure of the Atom

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The Structure of an Atom

Nucleus – center of the atom– Home of Protons and Neutrons



– Proton•Has a positive (+) charge•Has a relative mass of 1•Determines the atomic

number•Found inside the nucleus



– Neutron•Has no (0) charge•Has a relative mass of 1•Determines the isotope

– Isotopes are two of the same element with different masses

•Found inside the nucleus



– Electron•Has a negative (-) charge•Has a relative mass of 0•Determines the ion

– Cation (+ ion)– Anion (- ion)

•Found outside the nucleus



Subatomic Particle Location Relative Mass Charge

Proton NeutronElectron



Subatomic Particle Location Relative Mass Charge

Proton Inside Nucleus 1 +Neutron Inside Nucleus 1 0Electron Outside Nucleus 0 -


The Atom is Really, Really Small!

Just How Small Is An Atom?


The Periodic Table of Elements


The Periodic Table of Elements

• The elements are arranged by increasing

ATOMIC NUMBER!!• The horizontal rows are called periods and are labeled

from 1 to 7.• The vertical columns are called groups are labeled from

1 to 18.


Groups and Periods


What’s in a square?

Different periodic tables can include various bits of information, in different ways– atomic number– symbol– atomic mass– state of matter at

room temperature.– number of valence

electrons


Atomic Number

• Refers to how many protons an atom of that element has.

• No two elements, have the same number of protons.

• If they did they would be the same atom


Atomic Mass

• Refers to the “weight” of the atom.• It is derived at by adding the number of protons

with the number of neutrons.


Atomic Mass and Isotopes

• While most atoms of an element have the same number of neutrons, some don’t.

• E.g. Some Lithium atoms can have 3 neutrons while other can have 4

• Different number of neutrons means different atomic masses between isotopes


Isotope formulas

We write the symbol – mass (protons + neutrons)

Hydrogen H-1, H-2, H-3

Helium He-3, He-4

Lithium Li-6, Li-7


Valence Electrons

• Valence electrons are the electrons in the outer energy level (orbit) of an atom.

• These are the electrons that are transferred or shared when atoms bond together.

• How many valence electrons an atom has greatly affects its reactivity


Metals, Non-Metals and Metalloids

Please color your own table to match the picture


Properties of Periods and Groups

Atomic Radius• Sizes of the atoms (Atomic Radius) generally decrease as we move from left to right

across a period


Properties of Periods and Groups

Electronegativity• As you move from left to right across a period, the ability of the atom to attract another electron increases• This property is called electronegativity


Meet the Elements


Take out your second periodic table and pencil crayons and follow along


Families of the Periodic Table

Hydrogen• The hydrogen square sits atop Group 1, but it is not a

member of that family. Hydrogen is in a class of its own.

• It’s a gas at room temperature.• It has one proton and one electron in its one and

only orbit.



Alkali Metals• The alkali family is found in the first column of the periodic table.• Atoms of the alkali metals have a single electron in their outermost orbit, in other words, 1 valence electron.• They are shiny, have the consistency of clay, and are easily cut with a knife.• They are the most reactive metals.• They react violently with water.• Alkali metals are never found as free elements



Alkaline Earth Metals• They are never found uncombined in nature.• They have two valence electrons.• Alkaline earth metals include magnesium and calcium, among others.



Transition Metals• These are the metals you are probably most familiar: copper, tin, zinc, iron, nickel, gold, and silver.• They are good conductors of heat and electricity.



Halogen Family• The elements in this family are fluorine, chlorine, bromine, iodine, and astatine.• Halogens have 7 valence electrons, which explains why they are the most active non-metals. They are never found

free in nature.



Noble Gases• Noble Gases are colorless gases that are extremely un-reactive because their outermost orbit is full. • Because they do not readily combine with other elements to form compounds, the noble gases are called inert.• The family of noble gases includes helium, neon, argon, krypton, xenon, and radon. • All the noble gases are found in small amounts in the earth's atmosphere.



Rare Earth Elements• The thirty rare earth elements are composed of the lanthanide and actinide

series.


Elemental Funkiness video


The Bohr Model of the Atom

• An effective way to represent the first 20 elements• Each electron orbit is shown as a ring around the nucleus

The 1st orbit will hold a maximum of 2 electronsThe 2nd orbit will hold a maximum of 8 electronsThe 3rd orbit will hold a maximum of 8 electrons


Bohr-Rutherford Diagrams

1) Determine the number of electrons (= number of protons = atomic number)2) Place electrons in their proper orbit (2, 8, 8)

Ex/ He = 2 electrons Ne = 10 electrons

K = 19 electrons


What does it mean to be reactive?

• We will be describing elements according to their reactivity. • Elements that are reactive bond easily with other elements to make compounds.

What makes an element reactive?– An incomplete valence electron level (outer orbit).– All atoms (except hydrogen and helium) want to have 8 electrons in their very outermost energy level (this is called the rule of octet.)– Atoms bond until this level is complete. Atoms with few valence electrons lose them during bonding. Atoms with 6, 7, or 8 valence electrons gain electrons during bonding.

Chemistry Periodic Table and Bohr-Rutherford Diagrams.

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