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Atomic structure. Atomic Structure. ELECTRON – negative, mass nearly nothing. NEUTRON – neutral, same mass as proton (“1”). PROTON – positive, same mass as neutron (“1”).
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ELECTRON – negative, mass nearly nothing NEUTRON – neutral, same mass as proton (“1”) PROTON – positive, same mass as neutron (“1”) The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: The structure of the atom Dalton
The Atom Electron Nucleus Shell or Orbit
The Atom Hydrogen Proton Electron Hydrogen has one proton, one electron and NO neutrons
The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons
MASS NUMBER = number of protons + number of neutrons 4 He SYMBOL 2 PROTON NUMBER = number of protons (obviously) Mass and atomic number
The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons
The Atom Lithium Electrons Protons Neutrons
The Atom Beryllium Electrons Protons Neutrons Beryllium has four electrons, four protons and five neutrons.
The Atom Boron Electrons Protons Neutrons Boron has five electrons, five protons and six neutrons.
The Atom Carbon Electrons Protons Neutrons Carbon has six electrons, six protons and six neutrons.
The Atom Nitrogen Electrons Protons Neutrons Nitrogen has seven electrons, seven protons and seven neutrons.
The Atom Oxygen Electrons Protons Neutrons Oxygen has eight electrons, eight protons and eight neutrons.
The Atom Fluorine Electrons Protons Neutrons Fluorine has nine electrons, nine protons and ten neutrons.
The Atom Neon Electrons Protons Neutrons Neon has ten electrons, ten protons and ten neutrons.
The Atom Sodium Electrons Protons Neutrons Sodium has eleven electrons, eleven protons and twelve neutrons.
How many protons, neutrons and electrons? 1 11 16 H B O 1 5 8 23 35 238 Na Cl U 11 17 92
The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Mendeleev Periodic table Horizontal rows are called PERIODS
These elements have __ electrons in their outer shell E.g. all group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shells The Periodic Table Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number)
E.g. Lithium has 3 electron in the configuration 2,1 Sodium has 11 electrons in the configuration 2,8,1 Potassium has 19 electrons in the configuration __,__,__ The Periodic Table Fact 2: As you move down through the periods an extra electron shell is added:
These elements are metals This line divides metals from non-metals These elements are non-metals The Periodic Table Fact 3: Most of the elements are metals:
E.g. consider the group 1 metals. They all: • Are soft • Can be easily cut with a knife • React with water The Periodic Table Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY.
Potassium + water potassium hydroxide + hydrogen 2K(s) + 2H2O(l) 2KOH(aq) + H2(g) Group 1 – The alkali metals Some facts… 1) These metals all have ___ electron in their outer shell 2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily. 3) They all react with water to form an alkali (hence their name) and __________, e.g: Words – down, one, shell, hydrogen, nucleus
Group 0 – The Noble gases Some facts… 1) All of the noble gases have a full outer shell, so they are very _____________ 2) They all have low melting and boiling points 3) They exist as single atoms rather then diatomic molecules • Helium is lighter then air and is used in balloons and airships (as well as for talking in a silly voice) • Argon is used in light bulbs (because it is so unreactive) and argon , krypton and neon are used in fancy lights
Decreasing reactivity Cl Cl Group 7 – The Halogens Some facts… 1) Reactivity DECREASES as you go down the group (This is because the electrons are further away from the nucleus and so any extra electrons aren’t attracted as much). 2) They exist as diatomic molecules (so that they both have a full outer shell): 3) Because of this fluorine and chlorine are liquid at room temperature and bromine is a gas
H H Cl Cl Halogen + metal ionic salt Na + - Cl Na Cl Halogen + non-metal covalent molecule The halogens – some reactions 1) Halogen + metal: + 2) Halogen + non-metal: +
How shells fill • The first electron shell can only hold a maximum of two electrons. • The second electron shell can hold a maximum of eight electrons. • The third electron shell can also hold a maximum of eight electrons. • The fourth electron shell can also hold eight electrons.
39 K 19 Nucleus Electron structure Consider an atom of Potassium: Potassium has 19 electrons. These are arranged in shells… The inner shell has __ electrons The next shell has __ electrons The next shell has __ electrons The next shell has the remaining __ electron Electron structure = 2,8,8,1
The First Twenty Elements • Hydrogen 1,0,0,0 • Helium 2,0,0,0 • Lithium 2,1,0,0 • Beryllium 2,2,0,0 • Boron 2,3,0,0 • Carbon 2,4,0,0 • Nitrogen 2,5,0,0
First 20 Elements continued • Oxygen 2,6,0,0 • Fluorine 2,7,0,0 • Neon 2,8,0,0 • Sodium 2,8,1,0 • Magnesium 2,8,2,0 • Aluminium 2,8,3,0 • Silicon 2,8,4,0
First 20 Elements continued • Phosphorus 2,8,5,0 • Sulphur 2,8,6,0 • Chlorine 2,8,7,0 • Argon 2,8,8,0 • Potassium 2,8,8,1 • Calcium 2,8,8,2
The Alkali metals • Lithium, Sodium and Potassium have one electron in their outer shell and this is why they are found in group one of the periodic table.
The Nobel gases • The Nobel gases have full outer shells and they are found in group 0 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.
The Halogens • Fluorine, Chlorine, Bromine and Iodine are the Halogens and they all have seven electrons in their outer shell. This is why they are found in group 7 of the periodic table.
Displacement • Fluorine can displace Chlorine, Bromine and Iodine. F Cl Br I
Displacement • Chlorine can displace Bromine and Iodine but it cannot displace Fluorine Cl Br I F