1.4: The Periodic table and patterns of change Flashcards
How is the periodic table arranged as of 2014?
- reading left to right, arranged in order of increasing atomic number.
- 7 horizontal period and 18 vertical groups
What does the position of the elements mean?
Linked to physical and chemical properties, which allows for prediction
What are vertical columns called?
groups
What do the groups correspond to?
elements in the same group have similar chemical properties, they have the same amount of electrons in their outer shell
What are group 1 elements called?
Alkali metals
What do group 1 metals do in terms of reactions/reactivity?
They react with water to form hydrogen gas and an alkaline solution of the metal hydroxide.
What happens to reactivity as you go down group 1?
they become more reactive
What is the name of group 2?
Alkaline earth metals
What happens to reactivity as you go down group 2?
they become more reactive
What is the name of group 7/17?
halogens
What is important about group 7?
they are the most reactive non-metallic group
What happens to reactivity as you go down group 7?
reactivity decreases
what is the name of group 0?
noble gases
What happens to group 0?
They are inert/unreactive
What are the horizontal rows called?
periods
What do periods show?
The number of the period, gives the number of the highest occupied energy electron shell
What blocks are present on the periodic table?
s, d, f, p (same as orbitals)
What are elements that behave like both metals and non-metals called?
metalloids
Why are group 2 called alkaline earth metals?
Because they form an alkaline solution with water
What happens to group 2 in terms of atomic radius?
WHY?
It increases down the group
- number of electrons increases
- number of main electron shells increase
- more shielding to outermost electrons
- outer electrons repelled further from the nucleus
What happens to group 2 in terms of Ionisation Energies?
WHY?
decreases down the group:
- atomic radius increases
- number of main electrons shells increase
- more shielding to outermost electrons
- weaker nuclear attraction to outermost electrons
What happens to group 2 in terms of melting/boiling points?
WHY?
Decrease down the group:
- more shells and shielding
- weaker electrostatic attraction between positive cation
- less energy needed to overcome attraction
What happens to group 2 in terms of reactivity?
WHY?
increases down the group
- will lose 2 e- which requires energy
- outer electron (s) in shell further from nucleus
- more shielding
- weaker nuclear attraction
- outer electron(s) more easily lost
Metal + oxygen –>
metal oxide (basic oxide)
Metal + oxygen –>
example - magnesium
2Mg(s) + O₂(g) –> 2MgO (s)
Metal + oxygen –>
What is observed when magnesium reacts?
Bright white flame for Mg, white solid oxides formed
Metal + oxygen –>
example - calcium
2Ca(s) + O₂ –> 2CaO(s)
Metal + oxygen –>
what is observed when calcium reacts?
Red flame for calcium, white solid oxides formed
Metal + water –>
Metal hydroxide + hydrogen
Metal + water –>
example - magnesium
Mg(s) + 2H₂O(l) –> Mg(OH)₂ (aq) + H₂O
PH - 8/9
Metal + water –>
What is observed when magnesium reacts?
Very slow formation of bubbles of gas seen on the surface of magnesium
Metal + steam –>
Metal oxide + hydrogen (Mg only)
Metal + steam –>
example - magnesium
Mg(s) + H₂O –> MgO (s) + H₂(g)
Metal + steam –>
What is observed when magnesium reacts?
White solid formed
Metal + water –>
example - calcium
Ca(s) + 2H₂O(l) –> Ca(OH)₂(aq) + H₂
PH - 10/11
Metal + water –>
what is observed when calcium reacts?
Bubbles of gas and a white precipitate form
Metal + acid –>
metal salt + hydrogen
Metal + acid –>
example: calcium + hydrochloric acid
Ca(s) + 2HCl (aq)–> CaCl₂(aq) + H₂(g)
(calcium chloride + hydrogen)
Metal + acid –>
magnesium + sulfuric acid
Mg(s) + H₂SO₄(aq) –> MgSO₄(aq) + H₂(g)
Magnesium sulfate + hydrogen
Metal + acid –>
Barium + nitric acid
Ba(NO₃)₂(aq) + H₂(g)
Barium Nitrate + hydrogen
Metal + acid –>
what observations are seen?
Bubbles of gas (effervescence), metal dissolves to form a colourless solution
Metal oxide + Water –>
Metal hydroxide (all group 2)
Metal oxide + Water –>
example - Magnesium
MgO(s) + H₂O –> Mg(OH)₂ (aq)
Magnesium hydroxide
Metal oxide + Water –>
what is observed when magnesium reacts?
White solid dissolves
What molecules do halogens form?
Diatomic molecules
what kind of structure do halogens have and why?
The atoms are covalently bonded together so the halogens have a simple covalent structure
What happens to melting and boiling point as you go down group 2?
WHY?
Melting and boiling point increase
- More electrons
- stronger London forces
- more energy need to overcome attraction
What is the physical state of chlorine and fluorine at room temp?
gases
What is the physical state of bromine at room temp?
liquid
What is the physical state of iodine at room temp?
Solid
What kind of structure of halogens form?
simple molecular lattice
What happens to reactivity as you down group 7?
WHY?
decreases
- outer electron(s) in a shell further from nucleus
- more shielding
- weaker nuclear attraction
- electrons less easily gained
What happens to the atomic radius of the atoms as you go across each period?
WHY?
it get smaller
- increasing number of protons
- electrons are added to the same shell
- no extra shielding
- so a greater nuclear attraction for the outer shell of electrons to the nucleus
- atomic radius decreases
How are melting and boiling point determined?
By the structure and bonding of the substance
What Melting and boiling points do giant structures have?
WHY?
High
- strong attractive forces between particles that must be broken
- large amount of energy is therefore needed to break the bonds
What are giant structures?
Giant metallic / giant covalent
What Melting and boiling points do simple molecules and atoms have?
WHY?
Relatively low
- weak intermolecular forces between particles
- forces depend on number of electrons
- less energy is needed to overcome the intermolecular forces
Where are transition elements located on the periodic table?
with in the d-block (scandium through to zinc)
What is a d-block element?
An element with its outer electron in a d sub shell/orbital
What are transition metals?
An element that forms one or more stable ion which have a partially filled d-sub shell
What are the characteristics of transition metals?
- variable oxidation states
- acts as catalysts
- they form complex ions
- they form coloured compounds
Using the table in your book learn the bold oxidation states!
Transition metals
What is the oxidation number of: Fe²+
+
What transition elements act as catalysts?
iron, platinum, palladium, rhodium, nickel
What is iron used for?
Making ammonia (haber process)
What is platinum, palladium, rhodium used for?
Catalytic converters
What is nickel used for?
Making margarine, hydrogenation of vegetable oils
What is a complex ion?
A central metal ion surrounded by ligands
What is a ligand?
A molecule or ion that donates a lone pair of electrons to the central metal ion to form a dative covalent (coordinate) bond
What is a coordination number?
The number of dative covalent bonds around the central metal ion
What is an example of ligands?
H₂O : Cl - : NH₃
What do all transition metals form when dissolved in water?
Hexaaqua ion
What is the formula for hexaaqua ion?
[X(H₂O)₆]²+
What is the formula for a hexaaqua Cooper (II) complex?
[Cu(H₂O)₆]²+
What is the Cooper ion surrounded by (in hexaaqua Cooper (II) complex)?
6 water ligands
What does the water molecule donate in the hexaaqua Cooper (II) complex.
what does it form
Donates oxygen, to a lone pair of electrons to the central metal ions
- forms a dative covalent/coordinate bond
What is the shape of the hexaaqua Cooper (II) complex?
Octahedral
What is the coordinate number in hexaaqua Cooper (II) complex?
What is the bond angle?
6
90 degrees
What colour does copper ion form?
Blue solution
What is copper complex ion hexaaqua ion?
[Cu(H₂O)₆]²+
What colour does iron (II) form?
Pale green solution
What is iron (II) complex ion hexaaqua ion?
[Fe(H₂O)₆]²+
What colour does iron (III) form?
pale yellow solution
What is iron (III) complex ion hexaaqua ion?
[Fe(H₂O)₆]³+
