Today Atomic particles electrons, protons, neutrons Found inside the nucleus Atomic mass and atomic number

electron neutron proton

What is the structure of an atom? Nucleus – center of the atom Home of Protons and Neutrons Proton Has a positive (+) charge Has a relative mass of 1 Determines the atomic number Found inside the nucleus P

What is the structure of an atom? Neutron Has no (0) charge Has a relative mass of 1 Determines the isotope Isotopes are two of the same element with different masses Found inside the nucleus N

What is the structure of an atom? Electron Has a negative (-) charge Has a relative mass of 0 (zero) Determines the ion Found outside the nucleus Bohr model – electrons are in specific energy levels Electron cloud model – electrons are in a random cloud e

What is the structure of an atom? Bohr Model “Planetary Model” Schrödinger Model “Electron Cloud Model”

How are P, N, e- related? # protons = atomic number # electrons = # protons in a neutral atom # protons + # neutrons = atomic mass

Properties and atomic number Scientists discovered that the properties of elements seemed to depend on atomic number. What is the atomic number of an element? Atoms contain three types of particles: particle charge relative mass proton +1 1 neutron electron -1 0.0005 Where are these particles found in an atom?

What is atomic number? neutron electron helium nucleus proton What are the particles in this helium atom? neutron electron helium nucleus proton Atomic number = the number of protons in an atom What is the atomic number of helium?

Atomic number and electrons Atoms of elements contain equal numbers of protons and electrons. How does this affect the charge of such atoms? Atoms of elements have no charge, they are neutral. What is the charge on a fluorine atom? 19 F 9 9 protons 9 electrons 10 neutrons charge = +9 charge = - 9 charge = 0 total charge = 0 How are the number of electrons and atomic number related in a neutral atom? They are the same.

What is a chemical symbol? Chemical symbol tells us what atom it is Always a CAPITAL LETTER, sometimes followed by a lower case letter Ex: Oxygen O Nitrogen N Sodium Na *Cobalt – Co *Carbon Monoxide – CO (Co is an element, CO is a compound)

Charge (if ion) Atomic Number Symbol Atomic Mass

Hydrogen Protons: 1 Neutrons: 0 Electrons: 1 H 1 1

Sodium Protons: 11 Neutrons: 12 Electrons: 11 Na 23 11

Rhenium Protons: 75 Neutrons: 111 Electrons: 75 Re 186 75

Rhenium isotope Protons: 75 Neutrons: 112 Electrons: 75 Re 187 75

Cs 133 55 EXAMPLE Atomic number = protons and electrons How many protons, neutrons and electrons are found in an atom of 133 55 Cs Atomic number = protons and electrons There are 55 protons and 55 electrons Mass number = sum of protons and neutrons 133 – 55 = 78 There are 78 neutrons

Symbols Contain the symbol of the element, the mass number and the atomic number. 20

Symbols Contain the symbol of the element, the mass number and the atomic number. Mass number X Atomic number 21

F Symbols 19 9 Find the number of protons number of neutrons number of electrons Atomic number Mass Number 19 F 9 22

Br Symbols 80 35 Find the number of protons number of neutrons number of electrons Atomic number Mass Number 80 Br 35 23

Symbols if an element has an atomic number of 34 and a mass number of 78 what is the number of protons number of neutrons number of electrons Complete symbol 24

Symbols if an element has 91 protons and 140 neutrons what is the Atomic number Mass number number of electrons Complete symbol 25

Symbols if an element has 78 electrons and 117 neutrons what is the Atomic number Mass number number of protons Complete symbol 26

Why do atoms lose or gain electrons? Atoms give and take electrons to be stable. All atoms wants to have as many electrons as their nearest groups 18 atoms