An atoms ability to attract the electron pair in a covalent bond
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WHAT IS THE MOST ELECTRONEGATIVE ELEMENT
fluorine
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WHAT SCALE IS ELECTRONEGATIVITY MEASURED ON?
Paulings scale
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WHAT HAPPENS TO ELECTRONEGATIVITY WHEN YOU GO ACROSS AND UP THE PERIODIC TABLE
Electronegativity increases across and up. Across periodic table : nuclear charge increases and atomic radius decreases
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ARE NOBLE GASES INCLUDED IN ELECTRONEGATIVITY
Noble gases are not included as they tend not to form compounds
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WHAT ELEMENTS ARE MOST ELECTRONEGATIVE
Non metals, nitrogen, oxygen, fluprine and chlorine
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WHAT ARE THE LEAST ELECTRONEGATIVE ATOMS
Group 1 metals
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IF ELECTRONEGATIVITY DIFFERENCE IS LARGE- IS IT IONIC OR COVALENT
ionic - one bonded atom will have a much greater attraction for the shared pair than the other bonded atom. more electronegative atom will gain electrons
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COVALENT BONDS MAY BEPOLARISED BY DIFFERENCES IN ELECTRONEGATIVITY
the bonding electrons are pulled towards the more electronegative atome - making it polar. The difference in electronegativity causes a permanent dipole. greater the difference in electronegativity the more polar the bond
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WHAT IS A DIPOLE?
a dipole is a difference in charge bewteen two atoms caused by a shift in electron density.
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POLAR MOLECULES, CHARGE IS ARRANGED UNEVELY
polar molecules have permanent dipoles
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WHAT DETERMINES WHETHER OR NOT THE MOLECULE WILL HAVE AN OVERALL DIPOLE
The arrangement of polar bonds in amolecule determines whether or not the molecule will have an overall dipole
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WHAT HAPPENS IF THE POLAR BONDS ARE ARRANGED SYMMETRICALLY ?
if arranged symmetrically the dipoles will cancel each other out then the molecule will have no overall dipole and is non polar
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WHAT HAPPENS ID POLAR BONDS ARE ARRANGED SO THEY DONT CANCEL EACH OTHER OUT
the charge is arranged unevenly across the whole molecule, and it will have an overall dipole. molecules with an overall dipole are polar
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PURELY COVALENT
only bonds between atoms of a single element eg diatomic gases such as hydrogen can be purely covalent, this is because the electronegativity difference between the atoms are 0. so bonding e- are arranged completely evenly within the bond
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IONIC/ COVALENT
the higher the difference in electronegativity the more ionic in charcter the bondin becomes
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NON POLAR
the bonded e- pair is shared equally between the bonded atoms. It is polar : the bonded atoms are the same/ have the same or similar electronegativity
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POLAR
the bonded e- pair is shared unequally between the bonded atoms. It is polar when the bonded atoms are different and have different electronegativities- result in polar covalent bond
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HCL EXAMPLE- POLAR OR NON POLAR
Cl atom is more electronegative than the H atom. Cl has greater attraction for bonded pair of e- than H atom resultting in polar covalent bond. H-Cl bond is polarised
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CARBON DIOXIDE EXAMPLE - POLAR OR NON POLAR
It is non polar. C=O bonds have a permanent dipole. the 2 dipoles act in opposite directions. Dipoles cancel each other out, so overall dipole is 0
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INTERMOLECULAR FORCES - DEFINITION
weak interactions between dipoles of different molecules
imf - determine and are mainly responsible for the physical properties such as mp and bp. Covalent bonds determine the identity and chemical reactions of molecules.
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INDUCED DIPOLE-DIPOLE INTERACTIONS
e- in charge clouds are always moving quickly producing a changing dipole in a molecule
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STRENGTH OF INDUCED DIPOLE-DIPOLE INTERACTIONS (LF)
The more e- in each molecule the larger the instantaneous and induced dipoles. The greater the induced dipole-dipole interactions. The stronger the attractive forces between molecules. More e- means larger induced dipole more energy required.
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PERMANENT DIPOLE-DIPOLE INTERACTIONS
Act between the permanent dipoles in different polar molecules
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SIMPLE MOLECULAR SUBSTANCES
A simple molecular substance is made up of simple molecules- small unit containing definite number of atoms w/ definite molecular formular
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WHAT STRUCTURES DO SIMPLE MOLECULAR SUBSTANCES FORM
In solid state, simple molecules form a regular structure called a simple molecular latice.
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SIMPLE MOLECULAR LATTICE
the molecules are helf in place my weak IMF. the atoms within each molecule are bonded together strongly by covalent bonds
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Other cards in this set
Card 2
Front
WHAT IS THE MOST ELECTRONEGATIVE ELEMENT
Back
fluorine
Card 3
Front
WHAT SCALE IS ELECTRONEGATIVITY MEASURED ON?
Back
Card 4
Front
WHAT HAPPENS TO ELECTRONEGATIVITY WHEN YOU GO ACROSS AND UP THE PERIODIC TABLE
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