structure of the atoms
TRANSCRIPT
Structure of Atoms
You will learn about:
• Structure of atoms
• Isotopes
• Electron arrangement in atoms
• The Periodic Table
• Ions
contents
ParticleParticle Relative MassRelative Mass Relative Electric ChargeRelative Electric Charge
proton 1 +1
neutron 1 0
electron 1/2000 ≈ 0 -1
structure of atoms
three types of particles in an atom: proton, neutron and electron
composition
consists of a nucleus surrounded by electrons in shells
nucleus in turn contains protons and neutrons
structure of an atom:
composition
structure of atoms
number of protons is the proton number (atomic number)
number of electrons = number of protons ⇒ atom is electrically neutral
total number of protons and neutrons is the nucleon number (mass number)
+ -
structure of an atom
electrons in shells around nucleus
nucleus(protons + neutrons)
-
simplified structure of a typical atom:
simplified structure
structure of atoms
structure of a carbon atom
-
+6
6
6
nucleon number= 6 + 6 = 12
proton number= 6
-+
electron
proton
neutron
written in symbol form
symbol tells us that the atom
Cl
symbol form
structure of atoms
35
17proton number
nucleon number symbol of
the element
o is of element chlorineo has proton number 17 (so it contains 17 protons)o has 17 electrons (number of protons = number of electrons)o has nucleon number 35 (so number of protons + number of
neutrons = 35)o it must contain 35 – 17 = 18 neutrons
1111number of protons
23 - 11 = 12
11
24 – 11 = 13number of neutrons
11number of electrons
IsotopesIsotopes Na Na 2424
1111 Na Na 2323
1111
are atoms of the same element with different numbers of neutrons
same proton number but different nucleon numbers (mass numbers)
isotopesisotopes
have same chemical properties and form compounds with the same formula because they have the same number and arrangement of electrons
have small differences in physical properties
can be radioactive or non-radioactive
isotopesisotopes
82 and above
21
Maximum NumberMaximum Numberof Electronsof Electrons
Shell NumberShell Number
electron arrangement in atoms
electrons are arranged around the nucleus of the atom in shells
atomic nucleus (positive charge) attracts the electrons (negative charge) by an electrostatic force
each shell can hold a maximum number of electrons
electrons
electrons always go into the shell nearest to the nucleus, if there is room; otherwise they go to the next available shell
electronic structure & outer electrons
electron arrangement in atoms
is the arrangement of electrons in atoms
three ways of showing the electronic structure of a silicon atom:
full electronic structure
+ ---
-
-
-
- -
- -
-- + --
outer electronic structure
valency electrons
electronic structure
2.8.42.8.4
-
-
-
-
valence shell
electron arrangement in atoms
electronic structures of the first 20 elements:
electronic structure & outer electrons
2.4426Ccarbon
2.5527Nnitrogen
2.6628Ooxygen
2.7729Ffluorine
2.1123Lilithium
2.2224Beberyllium
2.3325Bboron
44thth shellshell
33rdrd shellshell
22ndnd shellshell
11stst shellshell
2
2
1
Number of Electrons inNumber of Electrons in
8Ne
He
H
SymbolSymbol
10
2
1
Proton Proton NumberNumber
1hydrogen
2.8
2
Simplified Simplified Electronic Electronic StructureStructure
neon
helium
ElementElement
electron arrangement in atoms
electronic structures of the first 20 elements:
electronic structure & outer electrons
2.8.668216Ssulphur
2.8.778217Clchlorine
2.8.888218Arargon
2.8.8.1188219Kpotassium
2.8.338213Alaluminium
2.8.448214Sisilicon
2.8.558215Ophosphorus
44thth shellshell
33rdrd shellshell
22ndnd shellshell
11stst shellshell
2
2
2
Number of Electrons inNumber of Electrons in
8
8
8
Ca
Mg
Na
SymbolSymbol
20
12
11
Proton Proton NumberNumber
8
2
1
2
2.8.1sodium
2.8.8.2
2.8.2
Simplified Simplified Electronic Electronic StructureStructure
calcium
magnesium
ElementElement
arrangement of elements in a table
periods show the elements arranged horizontally in order of proton number (atomic number)
across each period, the number of outer shell electrons increases from 1 to 8
groups show the elements with the same number of outer electrons arranged in vertical columns
the Periodic Table
the Periodic Table
group number
simplified electronic structure
I II III IV V VI VII
VIII
full electronic structure
the Periodic Table
the Periodic Table
proton numbername of element
symbol
ions
are charged particles; can be either positively or negatively charged
atoms form ions by gaining or losing electrons to obtain the electronic structure of a noble gas
ions
non-metallic
atom takes in electron(s)
Negative IonsNegative Ions
metallictype of atoms
atom loses electron(s)
movement of electrons
Positive IonsPositive Ions
ions
a negative ion is formed by gaining electrons to an atom
a positive ion is formed by losing electrons to an atom
ions
17
17
CCll atom atom
18
17
CCll-- ion ion
8
8
O atomO atom
10Number of electrons
8No of protons
OO2-2- ion ion
11
11
Na atomNa atom
10
11
NaNa++ ion ion
12
12
Mg atomMg atom
10Number of electrons
12No of protons
MgMg2+2+ ion ion
Proton Proton numbernumber
NeutronsNeutrons
ProtonsProtons
Positive Positive ionsions
Negative Negative ionsions
ElectronsElectrons
Nucleon Nucleon numbernumber
IsotopesIsotopes
Periodic Periodic TableTable
lose electrons lose electrons to becometo become
gain electrons gain electrons to becometo become
containcontain
havehave
shellsshellsmembers have members have
same number of same number of electrons in electrons in
which give out which give out radiation areradiation are
negative negative chargecharge
areare
is the sum ofis the sum of
containcontain
containcontain
are arranged in
are arranged in
outer outer shellshell
furthest from furthest from nucleus isnucleus is
electron electron arrangement isarrangement is
electronic electronic structurestructure
groupgroup
vertical vertical column iscolumn is
havehave
positive positive chargecharge
have different have different numbers ofnumbers of
radioactiveradioactive neutralneutral
containcontain
containcontain
nucleusnucleus
elements in elements in order oforder of
is the sum ofis the sum of
AtomsAtoms