Inside an AtomInside an Atom

The Atom As A ModelThe Atom As A Model

Structure of an AtomStructure of an Atom Atoms consist of protons, electron, Atoms consist of protons, electron,

and neutronsand neutrons Protons and neutrons make up the Protons and neutrons make up the

nucleusnucleus Protons: + chargeProtons: + charge Neutrons: neutralNeutrons: neutral

Electrons move around the nucleusElectrons move around the nucleus Electrons: (-) chargeElectrons: (-) charge They orbit the nucleus in energy levelsThey orbit the nucleus in energy levels # of protons and electrons are equal# of protons and electrons are equal

Structure of an AtomStructure of an Atom Atomic numberAtomic number

Number of protons in an elementNumber of protons in an element Hydrogen – Atomic number is 1Hydrogen – Atomic number is 1

Atomic massAtomic mass Amu – atomic mass unitAmu – atomic mass unit Total number of protons and neutrons in Total number of protons and neutrons in

an elementan element IsotopesIsotopes

Isotopes have the same number of protons Isotopes have the same number of protons but a different number of neutronsbut a different number of neutrons

Ex: carbon-12, carbon-13, and carbon-14Ex: carbon-12, carbon-13, and carbon-14

11

NaSodium

22.990

Problem

a.What is the atomic number?

b.What is the mass number?

c.How many electrons? Protons? Neutrons

Modern Periodic Modern Periodic ArrangementArrangement

Horizontal rows are called periodsHorizontal rows are called periods Vertical columns are called groups or Vertical columns are called groups or

families. families. These elements have similar propertiesThese elements have similar properties periodic table songperiodic table song

Electron SharingElectron Sharing

Covalent bond – a bond in which electrons Covalent bond – a bond in which electrons are shared between atoms to form are shared between atoms to form moleculesmolecules Both atoms will have 8 valence electronsBoth atoms will have 8 valence electrons

Ionic BondsIonic Bonds

An atom that has gained or lost an An atom that has gained or lost an electron is called an ionelectron is called an ion

Ions have an electrical chargeIons have an electrical charge

Ionic BondsIonic Bonds

What Happens When Chemicals React?

Some cool chemical reactions

Reaction of sodium and chlorine

Exothermic vs. EndothermicExothermic vs. Endothermic

Exothermic Exothermic reactions release reactions release heatheat Become warmerBecome warmer

Endothermic Endothermic reactions absorb reactions absorb heatheat Become coolerBecome cooler