The Periodic Table

Elements are arranged and identified on the periodic table by the number of protons they have in their nucleus.

The ATOMIC NUMBER is equal to the number of protons in an element.

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While the total number of electrons is important, it is even more important that you understand how many valence electrons an atom has.

What are valence electrons?

Valence electrons are the electrons in the outer energy level.

How many valence electrons do each of the following atoms have?

1 valence electron

2 valence electrons

3 valence electrons

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Elements in the same column or group have similar physical

and chemical properties.

This because they all have the same number of valence

electrons!

Reading Roman numerals:I = 1II = 2III = 3IV = 4V = 5VI = 6VII = 7VIII = 8

How many valence electrons do the elements of group 2 have?

II = 2You will ignore the A’s and B’s.

How many valence electrons do the elements of group 17 have?

VII = 7

How many valence electrons do the elements of group 14 have?

IV = 4

How many valence electrons do the elements of group 16 have?

VI = 6

How many valence electrons does phosphorous have?

V = 5

Remember: We can determine the number of valence electrons in the atom of an element by using the Roman numerals on the periodic table.

Lewis Dot Diagrams:Lewis dot structures show the number of valence electrons in an atom using an atoms symbol surrounded by dots representing the valence electrons. Use the Roman numerals on your periodic table to determine the number of valence electrons for elements below. Decide which Lewis dot diagram is an accurate representation.

Which Lewis Dot Diagram below accurately represents hydrogen?

H H H

Which Lewis Dot Diagram below accurately represents nitrogen?

N N NWhich Lewis Dot Diagram below accurately

represents carbon?

C C C

Which Lewis Dot Diagram below accurately represents boron?

B B BWhich Lewis Dot Diagram below accurately

represents phosphorous?

P P P

There are several things you will need to memorize about the periodic table.

Find the dark jagged line on the Periodic Table

On the left side of this line are all of the metals

On the right side of this line are

all of the nonmetals

Chemical reactions occur when atoms gain, lose, or share

electrons. Metals ________________ electrons.This always gives them a ____ charge.

lose or donate+

Nonmetals _________ electrons.This always gives them a ____ charge.

gain _

Nonmetal can also share electrons with one another, and this is what makes a covalent

compound.

You need to understand the pattern of elements gaining and losing electrons on the periodic table.

dona

te 1

ele

ctro

ndo

nate

2 e

lect

ron

gain

s 1

elec

tron

sD

oes

NO

T ga

in o

r los

e

gain

s 2

elec

tron

s

Think about counting from the outside to the inside!

Metals lose or donate electrons and nonmetals gain electrons

Because of this metals react with nonmetals!

sodium chlorinesodium chloride

+1 -1

sodium chlorinesodium chloride

+1 -1

We can see that it is a 1:1 ratio between sodium and chlorine, but why does it work out that way?

Once again, it has to do with the valence electrons!

Since sodium donates 1 electron and chlorine gains 1 electron, they join together in a 1:1 ratio.

This is true for all of the combinations of Group 1 and Group 17 elements!

HClLiFNaBrKFCsI

RbClHBrKClLiFRbBr

KBrNaILiClFrClHF

They are all 1:1 ratios!

magnesium sulfidemagnesium sulfide

+2 -2

This is also true between metals that lose 2 valence electrons and the nonmetals

that gain 2 valence electrons.

Since magnesium donates 2 electrons and sulfur gains 2 electrons, they join together in a 1:1 ratio.

This is true for all of the combinations of Group 2 and Group 16 elements!

BeOMgSSrOBaSeCaTe

CaSBeSeMgOSrSBaO

MgSeCaOBeSBaTeSrSe

They are all 1:1 ratios!

The Periodic Table can be used to determine the charge of all of the principal elements!

+1

+2 +3+4or-4 -3 -2 -1

0

The elements that lay on either side of the dark, jagged have rather unique properties. Sometimes they act like metals, and sometimes they act like nonmetals.

Because of this, they are called

Metalloids

The metals in the middle of the periodic table are known as the transition metals.

Transition Metals

There are several groups on the periodic table whose name you should have memorized.

Alka

li M

etal

sAl

kalin

e E

arth

Met

als

Hal

ogen

sN

oble

Gas

es

Group 1 = Alkali MetalsGroup 2 = Alkaline Earth MetalsGroup 17 = HalogensGroup 18 = Noble Gases

You also need to know that Iron, Cobalt, and Nickel have special properties such as the ability to be made into magnets. Together, these three elements are known as the .Iron Triad

Iron Triad

Which group on the periodic table undergoes the fewest chemical reactions?

Group 18The Noble Gases

They are inert gases. This is a chemical property that means they will not react with other substances.

Inert means inactive!

Ionic compounds are ALWAYS between a metal and a nonmetal.

On the left side of this line are all of the metals

On the right side of this line are

all of the nonmetals

Covalent compounds are ALWAYS between nonmetals.

On the right side of this line are

all of the nonmetals

Understanding the previous facts at a conceptual level is critical to your success in chemistry. Using this knowledge, determine the identity of each of the following unknown elements.

The formula above shows the ratio of an unidentified element, X, to chlorine in a covalent molecule. Which element below is most likely the identity of Element X?

A sodium B neon C phosphorous D copper

XCl3

Since it is a covalent molecule, it has to be a nonmetal. It cannot be neon since neon is an inert noble gas that would not react with chlorine.

The formula above shows the ratio of an unidentified element, X, to sodium in an ionic salt. In which group on the periodic table does Element X most likely belong?

A Group 1 B Group 2 C Group 17 D Group 18

NaX

Since it is an ionic salt, it has to be a nonmetal since sodium is a metal. It cannot be group 18 since group 18 is the inert noble gases that would not react with sodium.

The formula above shows the ratio of an unidentified element, X, to fluorine in an ionic salt. Which group below is most likely the identity of Element X?

A sulfur B lithium C arsenic D krypton

XF

Since it is an ionic salt, it has to be a metal since fluorine is a nonmetal.

The Law of Conservation of Mass

Scientist Mass of Reactant 1

Mass of Reactant 2

Mass of Product

Scientist A 19 g 22 g 42 g

Scientist B 19.4 g 22.4 g 41.7 g

Scientist C 19.36 g 22.37 g 41.74 g

Scientist D 19.364 g 22.372 g 41.736 g

According to the Law of Conservation of Mass, the mass of the reactants should equal the mass of the products.

Reactant 1 + Reactant 2 Product

Which scientist’s results below best support the Law of Conservation of Mass?

Hydrogen + Oxygen Water16.0 g 128 g ? g

16.0 grams of hydrogen reacts with 128 grams of oxygen. Assuming all of the reactants are used up, how much water will be produced?

Solving for MassWhen this concept is shown with a chemical equation,

nothing changes about how it should be solved.

16.0 g + 128 g = 144 g