Chapter 3 – Atoms and the Periodic TableChapter 3 – Atoms and the Periodic Table

ParticleParticle ChargeCharge MassMass LocationLocation

ProtonProton +1+1 1 amu1 amu In NucleusIn Nucleus

NeutronNeutron 00 1 amu1 amu In NucleusIn Nucleus

ElectronElectron -1-1 0 amu0 amu Outside Outside NucleusNucleus

The Structure of an Atom

amu = Atomic Mass Unit

Chapter 3 – Atoms and the Periodic TableChapter 3 – Atoms and the Periodic Table

An atom is mostly space with a very An atom is mostly space with a very small nucleus and an electron “cloud”small nucleus and an electron “cloud”

The number of protons is the The number of protons is the atomic atomic numbernumber on the periodic chart on the periodic chart

Example: C has 6 protonsExample: C has 6 protons

N has 7 protonsN has 7 protons

Au has 79 protonsAu has 79 protons

Chapter 3 – Atoms and the Periodic TableChapter 3 – Atoms and the Periodic Table

Mass #

Mass Number – is the mass of an atomMass Number – is the mass of an atom Atom’s mass = protons + neutronsAtom’s mass = protons + neutrons # neutrons = mass # - protons# neutrons = mass # - protons

Isotopes – atoms of the same element Isotopes – atoms of the same element that have a different number of neutrons.that have a different number of neutrons.

Isotopic NotationIsotopic Notation

Draw a diagram of each of the following isotopesDraw a diagram of each of the following isotopes

H-3H-3 H-2H-2 H-1H-1

Na-22Na-22 Na-24Na-24 Na-23Na-23

1. What is the charge on the nucleus of a Na atom?

2. What is the charge on the electron cloud of a Na atom?

3. What is the overall charge on the Na atom?

+11

-11

0

An atom that has gained or lost An atom that has gained or lost electrons is called an ion.electrons is called an ion.

A Na atom becomes an ion by the loss A Na atom becomes an ion by the loss of one electron. What will be the charge of one electron. What will be the charge on the sodium ion?on the sodium ion?

Sodium ion

11 protons +11

10 electrons -10

+1 net charge

Determine the charge on each of the following ionsDetermine the charge on each of the following ions

8p8p +8 +8 5p 5p +5 +5 9p9p +9 +910e10e -10 -10 2e 2e -2 -2 10e10e -10 -10

-2 -2 chargecharge +3+3 charge charge -1-1 chargecharge

Valence electrons – outer electrons Valence electrons – outer electrons that are involved in chemical reaction that are involved in chemical reaction (will be from 1 to 8 electrons).(will be from 1 to 8 electrons).

All chemical reactions are competition All chemical reactions are competition for these outer electronsfor these outer electrons

We show these outer electrons by We show these outer electrons by electron dot diagrams.electron dot diagrams.

LiLi BeBe BB FF NeNe

NaNa SrSr GaGa II KrKr

1869 Dimitri 1869 Dimitri Mendeleev arranged Mendeleev arranged the elements by the elements by increasing mass and increasing mass and by chemical properties.by chemical properties.

This was the first This was the first

periodic table of the periodic table of the elements.elements.

I developed the 1st periodic table

Family GroupsFamily Groups Nobel Gases (inert gases) Nobel Gases (inert gases)

Have 8 outer electrons. This fills their Have 8 outer electrons. This fills their outer orbitals and is very stable.outer orbitals and is very stable.

Nobel gases do not undergo Nobel gases do not undergo chemical reactionschemical reactions

Fluorine Family (the halogens)Fluorine Family (the halogens) Have 7 outer electronsHave 7 outer electrons Need one more electron to fill outer Need one more electron to fill outer

shellshell They react to take one electron from They react to take one electron from

another elementanother element

Oxygen FamilyOxygen Family Have 6 outer electronsHave 6 outer electrons They need two more electronsThey need two more electrons They react to take two more electrons from They react to take two more electrons from

another elementanother element

Alkali Metals (the Li family)Alkali Metals (the Li family) They have one outer electronThey have one outer electron They always react to lose this electronThey always react to lose this electron

Alkaline Earth Metals (the Be family)Alkaline Earth Metals (the Be family) These have two outer electronsThese have two outer electrons They always react to lose these two They always react to lose these two

electronselectrons

Elements can also be classified as Elements can also be classified as metals, nonmetals, and metalloidsmetals, nonmetals, and metalloids

MetalloidsMetalloids B, Si, Ge, As, Sb, Te, and AtB, Si, Ge, As, Sb, Te, and At Mark these on your chart!Mark these on your chart! These elements form a diagonal lineThese elements form a diagonal line Elements to the upper right of this line are Elements to the upper right of this line are

the nonmetalsthe nonmetals Elements to the lower left on this line are the Elements to the lower left on this line are the

metalsmetals Have properties in between metals & nonmetalsHave properties in between metals & nonmetals Semiconductors (conduct electricity poorly)Semiconductors (conduct electricity poorly)

MetalsMetals ShinyShiny Conduct electricityConduct electricity Are malleable (can be shaped by hammering)Are malleable (can be shaped by hammering) React with nonmetals to lose electronsReact with nonmetals to lose electrons

NonmetalsNonmetals Not shinyNot shiny Do not conduct electricityDo not conduct electricity Not malleableNot malleable React with metals to gain electronsReact with metals to gain electrons React with other nonmetals to share electronsReact with other nonmetals to share electrons