Learning Outcomes History of the idea of elements The contributions of the Greeks Boyle Davy and Moseley Greek Periodic Table Robert Boyle Element cannot be split up into simpler substances by chemical means ID: 431734
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1.1 Periodic TableLearning Outcomes
History of the idea of elements,
The contributions of the Greeks, Boyle, Davy and Moseley.Slide2
Greek Periodic TableSlide3
Robert Boyle
Element cannot be split up into simpler substances by chemical meansSlide4
Humphrey Davy
Used electrolysis to break down water into hydrogen and oxygen. Isolated potassium and sodium.Slide5
Henry Mosely
Measured No.of protons in the nuclei of atoms. Atomic number to arrange elements
.Slide6
Dobereiner
Saw trends and similarities among several groups of elements in threes
Triads = groups of 3 elements
Chlorine = 35.5, Bromine = 80, Iodine = 127 (average of
Cl
and I = 81)Slide7
Newlands
Tried to find some mathematical relation between the atomic weights of elements which were chemically similar
Groups called octaves
Arranged the elements in rows of seven
Eighth element had properties similar to the firstSlide8
“Law of Octaves” because of its similarity to musical octaves
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
K
Ca
?
?
As
Se
BrSlide9
Mendeleev Slide10
Dimitri Mendeleev
He suggested that the properties of the elements were a function of their atomic masses
Left gaps for undiscovered elements
Gave a name and predicted the properties of these yet to be discovered elements.Slide11
Mendeleev’ s TableSlide12
Learning OutcomesElements. Symbols of elements 1–36.The periodic table as a list of elements arranged to demonstrate trends in their physical and chemical properties.Brief statement of the principal resemblances of elements within each main group, in particular alkali metals, alkaline earth metals, halogens and noble gases.Slide13
Modern periodic tableThe elements are ordered by the number of protons ( Atomic Number) they have in their nucleus and not by their Atomic Weight.
Elements in the periodic table are arranged in periods (rows) and groups(columns). Atomic number increases as you move across a row or period.Slide14
Modern periodic tableSlide15
PeriodsThe period number of an element signifies the highest unexcited energy level for an electron in that element.Slide16
GroupsElements within a group share several common properties. Groups are elements have the same outer electron arrangement. The outer electrons are called valence electrons. Because they have the same number of valence electrons, elements in a group share similar chemical properties.
The Roman numerals listed above each group are the usual number of valence electrons. For example, a group VA element will have 5 valence electrons.Slide17
Classifying Elements- MetalsSlide18
MetalsMetals are lustrous (shiny), malleable (can be hammered)
are good conductors of heat and electricity. Slide19
Group 1: Alkali Metals Group 1: Alkali Metals
The alkali metals are located in Group IA (Sodium and potassium are examples of these elements.
Alkali metals form salts and many other compounds.
These elements are less dense than other metals, form ions with a +1 charge, and have the largest atom sizes of elements in their periods. The alkali metals are highly reactive. Slide20
Alkaline Metals 1 Learning outcomeDemonstration of the reaction with water of lithium, sodium
and potassium.Slide21
Group 1Very reactiveLow densitySoft-can be cut with a knifeBurn in air to form oxidesReact with water to form hydroxidesAlkali metalsSlide22
SodiumSodium + Oxygen Sodium oxideSodium + Water Sodium Hydroxide + Hydrogen gas
Stored in oil to prevent them from reacting with air or waterSlide23
Group 2: Alkaline Earth Metals The alkaline earths are located in Group IIA (second column) of the periodic table.
Calcium and magnesium are examples of alkaline earths. These metals form many compounds. They have ions with a +2 charge. Their atoms are smaller than those of the alkali metals. Slide24
Alkaline EarthsGroup 2ReactiveHarder than group oneBurn in air to form oxideReact with water to form hydroxidesSlide25
BerylliumSlide26
BariumSlide27
calciumSlide28
MagnesiumSlide29
StrontiumSlide30
RadiumSlide31
Group 17: Halogens The halogens are located in Group VIIA of the periodic table. Examples of halogens are chlorine and iodine. You find these elements in bleaches, disinfectants, and salts. These
nonmetals
form ions with a -1 charge. The physical properties of the halogens vary. The halogens are highly reactive. Slide32
HalogensGroup 7ReactiveChlorine, Bromine, IodineReact with hydrogen to form acidsSlide33
ChlorineGreen gasChlorine + Hydrogen Hydrogen Chloride gasHydrogen chloride gas dissolves in water to form Hydrochloric acid.
Chlorine reacts with sodium to form Sodium Chloride [Table Salt]Slide34
bromineSlide35
iodineSlide36
Group 18: Noble Gases The noble gases are located in Group VIII of the periodic table. Helium and neon are examples of noble gases. These elements are used to make lighted signs, refrigerants, and lasers. The noble gases are not reactive. This is because they have little tendency to gain or lose electrons. Slide37
Transition metalsSlide38
Transition MetalsThe transition elements are located in groups IB to VIIIB.
These elements are very hard, with high melting points and boiling points. The transition metals are good electrical conductors.
They form positively charged ions. Slide39
nonmetalsSlide40
Other tablesSlide41
Other tables