Atoms, molecules, bonding, periodic table

AtomsModern Atom Model

Nucleus-Protons and NeutronsElectrons around nucleus, never know the true

location

ProtonsPositively chargedIn nucleus

NeutronsNeutral (no) chargeIn nucleus

ElectronsNegatively chargedIn orbitals, or an electron cloud around the

nucleus

ElementsAtoms make up elements

The type of element depends on the atomic number, or the number of protons it has

Most elements occur naturally, but some have to be created in a lab

Periodic TableElements are organized on the Periodic Table

according to atomic number and properties of the element

Hydrogen

H1

1.0079

Atomic NumberNumber of protons

Number of electrons

SymbolUniversal abbreviations for the elements

Atomic MassMass of the protons and neutrons

Each proton equals 1 amu and each neutron equals 1 amu

Average number of neutrons in an atom = atomic mass – atomic number

States of MatterSolids, liquids, gases

Groups and PeriodsGroups = columns

Share similar properties

Periods = rowsAtomic number, number of protons/electrons,

and atomic mass increases from left to right

GroupsElements in the same column are in the same

group

Numbers on top indicate what group it is

GroupsNoble gases-Group 18

Halogens-Group 17

Alkali metals-Group 1

PeriodsRow of elements is in the same period

Only hydrogen and helium are in the 1st period

Number of protons increases from left to right

Number of electrons in the outer shell of the atom increases from left to right

On Your Periodic TableColor the solids, liquids, and gases a different

colorLabel groups and periods

Make a key!

Make sure you include:Atomic numberAtomic massSymbolName

Valence ElectronsNumber of electrons in the outermost orbital

Determine by the GROUP an element is in

Determines how an atom will bond with other atoms

Valence Electrons con’tGroup 1- 1 valence electron

Group 2- 2 valence electrons

Group 13- 3 valence electrons

Group 18- 8 valence electrons

All want to have 8 valence electrons in their outermost shell

Electron Dot DiagramsShow how many valence electrons an atom

has

Li

ClN

PracticeDraw electron dot diagrams for the following

atoms:PotassiumArgonSulfurBerylliumCarbonBromine

MoleculesWhen 2 or more atoms bond together

IonsIons are charged atoms

Happens when an atom gains or loses an electron

Examples:Cl gains 1 electron so it becomes negatively

charged, or Cl-

Na loses two electrons so it becomes positively charged, or Na2+

Ionic BondingAtoms with 5,6, or 7 valence electrons

usually become more stable when this number increases to 8

Atoms with 1, 2, or 3 valence electrons become more stable when they lose electrons

Ions that have opposite charges will attract and bond together forming an ionic bond

ExampleSodium has 1 valence electron

Chlorine has 7 valence electrons

If you combine them, Sodium will lose one electron and Chlorine will gain one electron. They both will be stable and have opposite charges so they will bond together.

And you will have Sodium Chloride, or salt! We would name this NaCl.

Bond With A ClassmateEach person has a card with an element on it.

Decide if you want to give away some electrons or if you want to take some electrons from someone else.

Find someone who wants to do the opposite and make a compound!

On your paper, write the name of the person you bonded with, draw electron dot diagram of the bonding, write the ion charges (positive and negative charge on each atom)

Covalent BondsCan oil and water mix? demo

Covalent BondsTwo atoms are sharing electrons

Both nuclei are attracting the electrons, which holds the atoms together

Molecules

PolarityPolar bond- electrons shared unequally,

molecule becomes charged, like water

Nonpolar bond- electrons shared equally, no charge on the molecule

Examples

F F OH

H

Metallic BondingAn attraction between a positive metal ion

and the electrons surrounding it

Metals lose electrons easily and form metal ions

A metal crystal consists of positively charged metal ions embedded in a “sea” of electrons

Metallic PropertiesGood heat conductor

Good conductor of electricity

Most metals are flexible and can be shaped easily

Metallic Properties VocabDuctile- Can be bent easily and pulled into

thin wires

Malleable- Can be rolled into thin sheets

Luster- Shiny and reflective

Properties of BondsIonic- Hard, brittle crystals with high melting

points, conduct electricity when dissolved in water

Covalent- lower melting points, low boiling points, do not conduct electricity when dissolved