THE PERIODIC TABLE

1869Dmitri Mendeleev – invented the periodic table

  • Made the first periodic table by arranging all known elements byatomic weight, chemical and physicalcharacteristics/properties and left blank spaces where he thought elements were missing
  • When he put the elements in groups according to their chemical and physical properties, he found a repeating pattern - he called an octet
  • His table was the start, but had some mistakes

1914 Henry Mosely – improved Mendeleev’s table

  • Used x-rays to count the number of protons in an atom
  • Found that different elements have different numbers of protons
  • Changed the periodic table by arranging his table by number of protons – atomic number instead of atomic weight,and chemical and physical properties

THE MODERN PERIODIC TABLE – is arranged by increasing atomic number (the number of protons)

PERIODIC TABLE

  • Atomic Number = the number of Protons
  • Atomic Mass = the total number of particles (protons and neutrons) in the nucleus
  • Chemical Symbol = the abbreviation for the element name
  • *NOTE: many element names are LATIN

GROUP OR FAMILY = the vertical columns on the table

Elements in the same group/family are similar

There are 10 families–including Hydrogen as its own family

Family/Group Family Elements Outer Level Electrons Reactivity

#1 Alkali Metals / Hydrogen,Lithium, Sodium / 1 / Most reactive metal
#2 Alkaline Earth Metals / Magnesium, calcium, radium / 2 / Highly reactive
#3 Transition Metals / Gold, Silver, Iron / 1, 2, or 3 / Less reactive
#4 Boron Family / Boron, Aluminum, Gallium / 3 / Less reactive
#5 Carbon Famil / Carbon, Silicon, Tin / 4 / Somewhat reactive
#6 Nitrogen Family / Nitrogen, Phosphorus, Arsenic / 5 / Somewhat reactive
#7 Oxygen Family / Oxygen, Sulfur, Selenium / 6 / Very reactive
#8 Halogens / Fluorine, Chlorine, Bromine / 7 / Most reactive non-metal
#9 Noble Gases / Helium, Neon, Argon / 8 / INERT – non-reactive
#10 Hydrogen / Hydrogen / 1 / Reactive

NOTE: The periodic table is arranged in vertical columns (called families or groups) with metals on the left, metalloids further right and non-metals on the far right…the table is made up mostly of metals

NOTE* Members of the same group have similar physical and chemical properties, so we sometimes call these groups families

NOTE: Chemical reactions are all about the ELECTRONS

NUMBER 8 is the magic number! All elements want to be STABLE and having 8 electrons on their

outer level makes themSTABLE. Recall that atoms have the same number of protons and electrons. In

chemical reactions, atoms gain or lose electrons in order to be STABLE with 8 on their outer level.

When this happens, they will have different numbers of electrons. Gaining or losing electrons will

turn the once neutral atom into an ION – which is an atom that is no longer neutral

Question WHY DO ELEMENTS REACT?

Answer - Its all about the ELECTRONS

Sodium has 11 protons and 11 electrons

2 on the K shell, 8 on the L shell, and 1 on the outer shell – its will readily react giving up its 1 OLE

Argon has 18 protons and 18 electrons

2 on the K shell, 8 on the L shell, and 8 on the outer shell – it will NOT react; Its last level is FULL at 8

Neon has 10 protons and 10 electrons

2 on the K shell, and 8 on the outer shell – Outer level is full, Will NOT react

Chlorine has 17 protons and 17 electrons

2 on the K shell, 8 on the L shell, and 7 on the outer shell – it will readily react by taking an electron in order to

Have a full outer shell …see Sodium above. It has one OLE so Chlorine will take Sodium’s electron in order to be stable. Chlorine had 7 OLE and needed 1 to have 8, so it will take chlorine’s 1 OLE

SHELLS

  • Electrons- Travel around the nucleus in orbitals or shells
  • The first shell – K shell – holds 2 electrons…then it is full
  • The second shell – L shell - holds 8 electrons until full
  • The third shell - M shell – holds 8 electron until full
  • The fourth shell - N shell – holds 18 electrons until full
  • The fifth shell -O shell – holds 18 electron until full
  • The sixth shell – P shell – holds 32 electrons until full
  • The seventh shell – Q shell – holds 32 electrons until full
  • Bigger shells (n-o-p-q) are actually made up of smaller shells called sub-orbitals
  • The outer shell is full at 8 electrons
  • In the transition metals, most of the electrons go into the sub-orbitals leaving only 1, 2, or 3 electrons on the last or outer shell

NOTE: Group number tells us how many electrons are on the last shell

Ex. Alkali Metals are all in group 1 and all have 1 OLE (outer level electron)

Alkaline Earth Metals are all in group 2 and all have 2 OLE

Transition Metals (groups 3 – 12) all have 1, 2, or 3 OLE

Boron Family (group 13) have 3 OLE

Carbon Family (group 14) have 4 OLE

Nitrogen family (group 15) all have 5 OLE

Oxygen family (group 16) all have 6 OLE

Halogens (group 17) all have 7 OLE

Noble Gases (group 18) all have 8 OLE

NOTE: All elements react except Noble Gases…they all have exactly 8 OLE and are STABLE.

All other elements are noble gas wannabees – nature loves stability and all want to be stable

So all other atoms want to be STABLE…like the noble gases…with 8 outer level electrons.

VALENCE

  • The charge of an atom after it gives or takes electrons
  • The number of electrons an atom will gain or lose in order to have a full shell (8 electrons)
  • All shells are considered full with 8 electrons
  • Atoms will gain or lose electrons – whichever is easier – to have exactly 8 electrons on it outermost level

Example: Sodium (Na) has 11 protons, 11 electrons – 2 on the first level, 8 on the second level and

1 electron on its outer level. It wants 8. Which is easier…to gain 7 or lose 1? Answer”

It is easier to lose one…so when that happens it will have 11 p It is no longer neutral.

It now has one less electron that number of protons. That means it is in a sense – less negative. Since it gave up 1 electron, (and became more positive) it now has a valence

of +1 (that 1 is the number of electrons it lost)

ION - an atom that is no longer neutral

Example: Calcium (Ca) has 12 electrons (and 12 protons) Remember! The protons determine what the

Element is. Calcium has 2 electrons on the first shell, the second shell is full with 8, the third shell is

Calcium’s outer shell and it has 2 electrons on it. REMEMBER! It wants 8. S0…it will LOSE 2

(which is easier that gaining 6) because it wants 8 on its outer level. Since it got rid of 2 electrons, it

became less negative and now has 12 protons, but only 10 electrons. It is no longer a neutral atom It

has become an ION with a valence of +2

Example: Chlorine has 17 protons and 17 electrons.

Shell one has 2 electrons and is full. Shell 2 has 8 and is full. Shell 3 can hold 8, but there are only

7 electrons left. So chlorine wants to be full with 8…it will be easier to GAIN 1 electron that to lose

7 electrons. So Chlorine will look to GAIN 1 electron to make it stable with 8. It is no longer neutral.

It now has 17 protons and 18 electrons. Since it gained an electron to make it more stable, it has

Become more negative and is no longer an atom. It is now an ion with a valence of -1

RE – CAP

  • Elements will give or take electrons to have a full outer shell
  • Valence – tells how many electrons the element will give or take

THE PERIODIC TABLE IS MADE UP OF METALS, NON-METALS AND METALLOIDS

1.METALS –

  • Located left side of the table
  • Usually 3 or fewer electrons in the last shell
  • Shiny
  • Good conductors of heat and electricity
  • Solids at room temp…EXXCEPT…mercury (Hg)
  • Malleable and ductile
  • All have a valence of +1, +2, or +3

NOTE: Metals all have a positive valence

Metals areELECTRON GIVERS

2.NON-METALS

  • Located on right side of the table
  • Usually 5 or more electrons in the last shell
  • Not shiny
  • Poor conductors of heat and electricity
  • Good insulators
  • Solids and gases at room temp…EXCEPT…Bromine
  • Brittle
  • All have negative valences
  • Non-Metals are all ELECTRON TAKERS

3.METALLOIDS

  • Located along the zigzag line on the table
  • Usually 3 – 6 electrons in the last shell
  • Some shiny - some dull
  • Some are poor conductors of heat and electricity - some are conductors
  • They are solids at room temp
  • Some are brittle
  • Their properties can change with temp
  • Metalloids are great for use in electronic device

VOCABULARY TERMS TO KNOW

  • Equationa method of showing what happens in a chemical reaction
  • Formulathe elements present in a compound
  • Reactantsthe elements that react together in a chemical reaction (on the right)
  • Productswhat is formed in a chemical reaction (on the left)
  • Elementa pure substance that cannot be broken down into simpler substances
  • Compoundtwo or more different elements that combine
  • Valencethe number of electrons an element gives or takes in a chemical reaction
  • Ion an atom that is no longer neutral
  • Bondan invisible force that causes elements to join together in a chemical reaction
  • Atomic Numberthe number of protons in an element
  • Atomic massthe total number of particle (protons and neutrons) in the nucleus
  • Chemical Symbolthe abbreviation for the element name (many in Latin)
  • Periodic Tablemade up of metals, metalloids, non-metals (mostly metals)
  • Full levelall shells are considered full with 8 outer level electrons
  • Metalsmetals give electrons
  • Non-Metalstake electrons
  • Chemical Equationmade up of the reactants (on the right side of the =) and the products on the left
  • Isotopeatoms of the same element with different numbers of neutrons and atomic weight…ex… Chlorine 35 and Chlorine 36
  • InertTotally non-reactive

CHEMICAL EQUATIONS– a method of showing what happens in a chemical reaction

  • Metals lend/give electrons
  • Non-Metals take electrons

Example: Sodium (Na) -metal+Chlorine (Cl) –non-metal

11 protons, 11 electrons17 protons, 17 electrons

2,8,12,8,7

Sodium will give the oneChlorine will take the one electron

Electron to Chlorine and havefrom Sodium to have a full outer

A full outer shell (stable)shell (stable)

Sodium has lost an electronChlorine has gained an electron

The Sodium atom will stick to the Chlorine atom by forming a BOND

Sodium and Chlorine are joined specifically by an IONIC BOND

It is no longer Sodium or Chlorine

It is now a Compound

The protons and electrons are able to cancel each other out…so the compound is NEUTRAL

SO……..The first thing that happened is the sodium and chlorine atoms bumped into each other

Chlorine needed an electron and gained an electron

Sodium needed to give away an electron and did

The chlorine atom is no longer neutral because it has gained an electron making it an ion with a

-1 charge

The sodium atom is no longer neutral because it gave away an electron making it too and ion with

a +1 charge.

The sodium atom will stick to the chlorine atom by forming a BOND

More specifically, sodium and chlorine are now joined by an ionic bond

It is no longer chlorine or sodium

It is now an entirely new substance – a compound with entirely new properties that are different

than the properties of either sodium or chlorine.

Example: Chlorine is a poisonous green gas

Sodium is a highly reactive silver-colored metal

When ionic ally bonded they form a whole new substance –common table salt that is

harmless (NaCl)

4 STEPS IN AN IONIC REACTION

  1. Atoms must BUMP into each other
  2. Metals will give away electrons and non-metals will gain electrons
  3. The neutral atoms turn into IONS
  4. The atoms stick together as the opposite charges cause an ionic bond to form

METALS – lend or give away electrons

NONMETALS – borrow or take electrons

Positive valences react with negative valences

Example: Ba + S yields BaS(Barium Sulfide)

Explanation: Barium has a valence of +2 and Sulfur has a valance of -2

They will bond to form Barium Sulfide

AL + FyieldsALF(Aluminum Fluoride)….BUT the formula is NOT right)

Explanation: Aluminum has a valence of +3 and Fluorine has a valence of -1

It will take 3 Fluorine atoms to satisfy 1 Aluminum

The correct formula for Aluminum Fluoride is AlF3

BONDS – A bond is an invisible force that holds things together

There are 3 Types of Bonds (there are really more, but we will study just these three)

  1. Ionic Bonds – A metal and a non-metal combine by trading electrons
  2. Covalent Bonds – A non-metal and a non-metal combine by sharing electrons
  3. Metallic Bonds – A metal and a metal combine

Note*

  • Metallic Bonds are very strong physically and very weak chemically
  • Metals want to get rid of electrons
  • The atoms will stick together, but don’t make anything new – i.e. they will mix, but don’t really

react and they don’t make a new substance

RADICALS

  • Radicals are polyatomic (made up of many atoms) ions that cannot be found on the periodic table.
  • You must get their valences from a chart
  • These are compounds that have come together and DO NOT want to separate.
  • They ACT AS ONE