Atomic Structure Chemistry- power point adapted from Charles
Page High School Stephen L. Cotton /R Wolfendale/ Derek Stacy Slide
2 Defining the Atom OBJECTIVES: OBJECTIVES: Describe the structure
of an atom Describe the structure of an atom Outline development of
atomic models Outline development of atomic models Atoms/ions-the
difference Atoms/ions-the difference Using chemical formulas to
identify ionic compounds Using chemical formulas to identify ionic
compounds Distinguish between chemical and nuclear reactions
Distinguish between chemical and nuclear reactions Compare protons,
neutrons and electrons Compare protons, neutrons and electrons
Describe how Alpha and Beta particles and Gamma radiation are
released from unstable atoms Describe how Alpha and Beta particles
and Gamma radiation are released from unstable atoms Slide 3 The
Atom- SW pg69 + P 4+ Everything is made of atoms -WOOD, GLASS, SKIN
Everything is made of atoms -WOOD, GLASS, SKIN They are so small
you cannot see them even with a microscope They are so small you
cannot see them even with a microscope There are 118 known types of
atoms, 91 that are natural on earth, the other 27 made in the lab
There are 118 known types of atoms, 91 that are natural on earth,
the other 27 made in the lab Atoms are listed smallest to largest
on the periodic table Atoms are listed smallest to largest on the
periodic table Each square has the atom, its chemical name and
symbol Each square has the atom, its chemical name and symbol
(students to receive periodic table to stick in book and blank one
to label later (students to receive periodic table to stick in book
and blank one to label later Slide 4 Elements Pure substances can
be further classified as elements and compounds. Pure substances
can be further classified as elements and compounds. Elements are
the building blocks of all other substances. Elements are the
building blocks of all other substances. Elements consist of atoms
of the same type and are represented separately on the periodic
table. Elements cannot be broken down further by chemical
processes. E.g. calcium, oxygen, zinc, chlorine, carbon, iron, etc
Year 9 Science 4 Slide 5 Slide 6 Common elements Phosphorus-P4
Oxygen-O2 Buckyball- carbon 60 Made of 60 Carbon atoms in the shape
of a soccer ball Slide 7 Molecules Elements are made up of
characteristic atoms and they can join together to form discrete
groups of atoms called molecules. It is often in a grid or crystal
lattice like structure Two hydrogen atoms can join with an oxygen
atom to form a water molecule. H 2 O Year 9 Science 7 Slide 8
Crystal Lattice Silicon and oxygen atoms form crystal lattices to
make beach sand! Depending on how big the sand grain-determines how
many atoms Silicon and oxygen atoms form crystal lattices to make
beach sand! Depending on how big the sand grain-determines how many
atoms Slide 9 Compounds Compounds are pure substances that can be
broken down further by chemical reactions. E.g. water, sugar,
polythene, propane, sodium chloride, etc, Water (H 2 O) can be
broken down into the elements hydrogen and oxygen by the process of
electrolysis. waterhydrogen + oxygen Year 9 Science 9 electricity
Slide 10 Compounds Sodium chloride (NaCl) a compound, called a
crystal lattice, can be broken down into the elements sodium and
chlorine, also by electrolysis. sodium chloridesodium + chlorine
Year 9 Science 10 electricity Slide 11 Compounds Compounds can also
be synthesised (man made) by reacting elements together. A compound
is defined as having more than one type of atom. When hydrogen is
burned in oxygen water is produced. hydrogen + oxygen water Year 9
Science 11 Slide 12 Compounds Compounds have very different
properties to those of the elements that make them up. Sodium (Na)
: very active metal Chlorine (Cl 2 ): a poisonous gas Sodium
chloride (NaCl): our bodies need for cellular processes. + +
sodiumchlorinesodium chloride Year 9 Science 12 Slide 13 Inside the
Atom Slide 14 Atoms Protons and neutrons exist in the central part
of the atom called the nucleus. Electrons orbit the nucleus in
energy levels called shells. Electrons cannot exist in the nucleus.
They are much smaller and move very fast This speed of the
electrons forms an electron cloud Year 9 Science 14 Slide 15
Subatomic Particles ParticleCharge Mass (g) Location Electron (e -
) (e - ) 9.11 x 10 -28 9.11 x 10 -28 Electron cloud Proton (p + )
+1 1.67 x 10 -24 1.67 x 10 -24Nucleus Neutron (n o ) (n o )0 1.67 x
10 -24 1.67 x 10 -24Nucleus Slide 16 Atoms The number of protons in
the nucleus is characteristic of the element and is called the
atomic number. All hydrogen atoms have 1 proton. All uranium atoms
have 92 protons. Etc. Year 9 Science 16 Slide 17 Atomic Number The
number of protons in the nucleus of an atom= Atomic Number the
number you see on the periodic table above the symbol/name Number
of protons and neutrons in the atoms nucleus is the MASS number
Slide 18 Isotopes Frederick Soddy (1877-1956) proposed the idea of
isotopes in 1912 Frederick Soddy (1877-1956) proposed the idea of
isotopes in 1912 Isotopes are atoms of the same element having
different masses, due to varying numbers of neutrons. Soddy won the
Nobel Prize in Chemistry in 1921 for his work with isotopes and
radioactive materials. Soddy won the Nobel Prize in Chemistry in
1921 for his work with isotopes and radioactive materials. Slide 19
Isotopes Sometimes atoms of the same element have different numbers
of neutrons from one another- e.g. Helium has generally 2 protons/2
neutrons Mass number = 4 in this case However there is a HELIUM 3 2
PROTONS AND 1 NEUTRON Mass= 3 When the atomic number is the same
but mass number different for the same element- it is called an
Isotope Slide 20 Isotopes cont: Almost all elements have two
isotopes Almost all elements have two isotopes Some have many more
Some have many more Most common isotope is Hydrogen 1 = 1 proton in
nucleus and no neutron Most common isotope is Hydrogen 1 = 1 proton
in nucleus and no neutron Makes up 99.98 % of the hydrogen on
earth-called protium Makes up 99.98 % of the hydrogen on
earth-called protium Hydrogen 2 is deuterium, and Hydrogen 3 =
tritium Hydrogen 2 is deuterium, and Hydrogen 3 = tritium It is the
isotopes of hydrogen that are used in nuclear power plants to
generate power more efficiently It is the isotopes of hydrogen that
are used in nuclear power plants to generate power more efficiently
Slide 21 Isotopes are atoms of the same element having different
masses, due to varying numbers of neutrons.
IsotopeProtonsElectronsNeutronsNucleus Hydrogen1 (protium)
(protium)110 Hydrogen-2(deuterium)111 Hydrogen-3(tritium)112 Slide
22 A look back then!Defining the Atom The Greek philosopher
Democritus (460 B.C. 370 B.C.) was among the first to suggest the
existence of atoms (from the Greek word atomos) The Greek
philosopher Democritus (460 B.C. 370 B.C.) was among the first to
suggest the existence of atoms (from the Greek word atomos) He
believed that atoms were indivisible and indestructible He believed
that atoms were indivisible and indestructible His ideas did agree
with later scientific theory, but did not explain chemical
behaviour, and was not based on the scientific method but just
philosophy His ideas did agree with later scientific theory, but
did not explain chemical behaviour, and was not based on the
scientific method but just philosophy Slide 23 Thomsons Atomic
Model Thomson believed that the electrons were like plums embedded
in a positively charged pudding, thus it was called the plum
pudding model. J. J. Thomson Slide 24 Daltons Atomic Theory
(experiment based!) 3)Atoms of different elements combine in simple
whole-number ratios to form chemical compounds 4)In chemical
reactions, atoms are combined, separated, or rearranged but never
changed into atoms of another element. 1)All elements are composed
of tiny indivisible particles called atoms 2)Atoms of the same
element are identical. Atoms of any one element are different from
those of any other element. John Dalton (1766 1844) Slide 25 Sizing
up the Atom Elements are able to be subdivided into smaller and
smaller particles these are the atoms, and they still have
properties of that element If you could line up 100,000,000 copper
atoms in a single file, they would be approximately 1 cm long
Despite their small size, individual atoms are observable with
instruments such as scanning tunneling (electron) microscopes Slide
26 Section 4.2 Structure of the Nuclear Atom One change to Daltons
atomic theory is that atoms are divisible into subatomic particles:
One change to Daltons atomic theory is that atoms are divisible
into subatomic particles: Electrons, protons, and neutrons are
examples of these fundamental particles Electrons, protons, and
neutrons are examples of these fundamental particles There are many
other types of particles, but we will study these three There are
many other types of particles, but we will study these three Slide
27 Discovery of the Electron In 1897, J.J. Thomson used a cathode
ray tube to deduce the presence of a negatively charged particle:
the electron Slide 28 Modern Cathode Ray Tubes Cathode ray tubes
pass electricity through a gas that is contained at a very low
pressure. TelevisionComputer Monitor Slide 29 Mass of the Electron
1916 Robert Millikan determines the mass of the electron: 1/1840
the mass of a hydrogen atom; has one unit of negative charge The
oil drop apparatus Mass of the electron is 9.11 x 10 -28 g Slide 30
Conclusions from the Study of the Electron: a)Number of electrons =
number of protons: This means atoms have a neutral charge because =
+ve charges = - ve charges b)Electrons have so little mass = they
are so small that atoms contain electron clouds (all the electrons
flying round the nucleus) these can be huge -1000 X wider than the
nucleus c)Most of an atom is therefore empty space Slide 31
Conclusions from the Study of the Electron: In New Zealand a
scientist Earnest Rutherford discovered that the nucleus took up
such a small space inside the atom He fired a beam of helium
nuclei)alpha particles, into a piece of gold foil most passed
through to his surprise! Some deflected back Up till now most
scientist thought atoms were quite solid Slide 32 Ernest
Rutherfords Gold Foil Experiment - 1911 Alpha particles are helium
nuclei - The alpha particles were fired at a thin sheet of gold
foil Particles that hit on the detecting screen (film) are recorded
Slide 33 Electrons.. The electrons are attracted to the nucleus by
the protons in the nucleus because of their opposite charges Why
dont they fall into the nucleus?....they are trapped in electron
shells These are a little like layers on an onion Many of the
shells in an atom are empty as obviously many atoms do not have
many electrons Electrons have set numbers than can be held in each
shelli.e the first shell and smallest holds two The next can hold
8, the third is 18, 4 th is 32 and so onworks on a formula 2n
squared The number of electrons in each shell is the ELECTRON
CONFIGURATION I.E Sodium is 2:8:1 as it has 11 electrons.. Slide 34
Structure of the Nuclear Atom Practical pg 11 (P) Experimenting
like Rutherford Practical pg 11 (P) Experimenting like Rutherford
Describe the structure of atoms, according to the Rutherford atomic
model. Describe the structure of atoms, according to the Rutherford
atomic model. Slide 35 Some revision- before Ions! Complete Symbols
Element, the mass number and the atomic number. Element, the mass
number and the atomic number. X Mass number Atomic number Subscript
Superscript Slide 36 Symbols n Find each of these: a) number of
protons b) number of neutrons c) number of electrons d) Atomic
number e) Mass Number Br 80 35 Slide 37 Symbols n If an element has
an atomic number of 34 and a mass number of 78, what is the: a)
number of protons b) number of neutrons c) number of electrons d)
complete symbol Slide 38 Symbols n If an element has 91 protons and
140 neutrons what is the a) Atomic number b) Mass number c) number
of electrons d) complete symbol Slide 39 Symbols n If an element
has 78 electrons and 117 neutrons what is the a) Atomic number b)
Mass number c) number of protons d) complete symbol
