Block 1 - The Periodic Table Flashcards by Christina Elliott

What are the alkali metals

group 1 metals

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What is a primary use of the alkali metals

As cations for OH- and CO32- ions because these ions are important in many reactions but do not dissolve in water readily apart from when bonded to the alkali metals

The alkali metals also won’t react with the intended reactants for the OH- and CO32- ions

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describe the appearance of alkali metal halides

white crystalline solid

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what are the characteristics of alkali metal halides

high melting temperature
melts are electrically conductive
dissolve in water to form colourless solutions which conduct electricity

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what oxide does lithium form

Li2O

lithium burns with a lilac flame

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what oxide does sodium form

Na2O2

O22- peroxide ion

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what oxide do potassium rubidium and caesium form

MO2

O2- ion (small 2 at the bottom, single -ve charge)
superoxide ion

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what happens when alkali metals are heated gently with H2

colourless crystal hydride MH formed

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what is the appearance of fluorine

yellow gas

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what is the appearance of chlorine

green-yellow gas

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what is the appearance of bromine

deep red liquid

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what is the appearance of iodine

shiny black solid

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what happens when hydrogen halides dissolve in water

acid is formed

HF forms a weak acid (because H3O+ and F- ions form hydrogen bonds), the rest form strong acids

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what are the possible valencies of the halogens

1,3,5,7

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how do the halogens react with aluminium

AlX3 formed

AlF3 is ionic
AlCl3 is layered
AlBr3 and AlI3 are covalent dimers Al2X6

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why are the noble gasses unreactive

they all have a full outer shell of electrons

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what is unique about radon

it is alpha active so can cause damage if inhaled

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how does metallic character vary down a group

increases

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how does metallic character vary across a period

decreases

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how does the maximum valency vary down a group

no change

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how does the maximum valency vary across a period

increases

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how does the melting temperature of group 1 and 2 metals vary down a group

decreases apart from Ca

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how does the melting temperature of group 1 and 2 metals vary across a period

increases

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how does the density of group 1 and 2 metals vary down a group

decreases apart from Li

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how does the density of group 1 and 2 metals vary across a period

increases

how does the reactivity of group 1 and 2 metals vary down a group

increases

how does the reactivity of group 1 and 2 metals vary across a period

decreases

what is Hund's rule

in any sub shell there will be the maximum number of electrons with spins of the same sense this leads to ground-state arrangements (think monopoly)

what is valency

the combining power of an element | however valence electrons refers to the number of electrons in the outer shell

what are the 4 ways to define oxidation

addition of oxygen removal of hydrogen loss of electrons increase in oxidation number

what are the 4 ways to define reduction

removal of oxygen addition of hydrogen gain of electrons decrease in oxidation number

what is the rule for F when calculating oxidation number

always -1

what is the rule for O when calculating oxidation number

-2 apart from in F2O

what is the rule for H when calculating oxidation number

+1 apart from hydrides of elements with lower electronegativity (group 1)

what is the rule for Cl, Br and I when calculating oxidation number

-1 apart from when with O or other halogens

what is the lewis definition of an acid

a lone pair acceptor

what is the lewis definition of a base

a lone pair donor

what is the Arrhenius definition of an acid

a substance which contains hydrogen and releases H+ ions when dissolved in water

what is the Arrhenius definition of a base

a substance which releases OH- ions when dissolved in water

what is the Brønsted–Lowry definition of an acid

a proton donor

what is the Brønsted–Lowry definition of a base

a proton acceptor

what is the steric effect

when the shape of a molecule blocks bonding/reaction

define repulsion axis

each pair of electrons (bonded or non bonded) | they define the shape of a molecule

what are the rules regarding the strength of different inter-axis repulsion

lone pair-lone pair > lone pair-bond pair > bond pair-bond pair triple bond > double bond > single bond interactions at 90 degrees are stronger than those at 120 degrees

what is special about lone pair positioning in trigonal bypyramidal shapes

they occupy equatorial positions (to limit interactions at 90 degrees) leads to a T-shaped molecule

what shape and bond angle does a molecule with 3 atoms take

linear | 180

what shape and bond angle does a water molecule take

V-shaped | 104.5

what shape and bond angle does a molecule with 4 atoms take

trigonal planar | 120

what shape and bond angle does a molecule with 5 atoms and a lone pair take

pyramidal | 107.8

what shape and bond angle does a molecule with 5 atoms take

tetrahedral | 109.5

what shape and bond angle does a molecule with 6 atoms take

trigonal bipyramidal | 90 and 120

what shape and bond angle does a molecule with 7 atoms take

octahedral | 90

what shape and bond angle does a molecule with 8 atoms take

pentagonal bipyramidal | 90 and ?

what shape and bond angle does a molecule with 4 atoms and 2 lone pairs take

square planar

what is the bond angle in an alkene

122 from the carbon double bond to the hydrogen | 117 between the hydrogens

what shape does a molecule with 6 atoms and a lone pair take

square pyramidal

define electronegativity

the power of an atom to attract electrons

what are the trends in electronegativity in the periodic table

increases up and across the table | therefore metals have lower electronegativity than non-metals

how is electronegativity measured

on the Pauling scale

what electronegativity difference is the threshold for ionic bonding

one element >2 and the other <1.9

what is the dipole moment and how is it calculated

it is the extent of charge separation (μ) μ = qr ``` q = charge at the positive end (C) r = distance between charges (m) ```

what is 2 debye (D) equal to

3.336x10^-30Cm

what are dipole moments affected by

electronegativity difference | position of non-bonded electron pairs

what are London dispersion forces and what is their trend down a group

forces between instantaneous dipole and induced dipole they increase down a group

what is a resonance hybrid

each bond is a mix of dative and normal covalent bond so the bond length is somewhere between

when does hydrogen bonding occur and how does its strength change down a group

when a H is bonded to the lone pair of electrons on N, O or F strength decreases down a group

how are the electrons described in metallic bonding

electron gas group 1 and 2 and aluminium all bond this was Al is the bet electrical conductor since it has 3 electrons free to move