A Level Chemistry - 1.3 Bonding

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dissolved "This is because when a solid, the ions are not free to move and carry the charge through the structure, but when molten of dissolved they a are charge STAESS |_ion is, this makes ionic 20 wit repel each other, and the structure will break ·compounds brittle 0 O 7 1.3.2 NATURE OF COVALENT & PATIVE COVALENT BONOS COVALENT BOND-pair of elections shared between 2 atoms ・It is the electrostate force of attraction between the + nucles pair of election, and a shared - Covalent bonds should not be regarded as shared electron in a fixed position.. • state of constant motion, best regarded as charge clouds Electrons pain in are in a - Multiple covalent boods (eg. double) contain multiple e pour STRENGTH OF GOVALENT BONDY - All covalent bonds are considered generally strong - The smaller the atoms, the closes the elections are to the 2 nuclei, the shorter the bond, the stronger the bond COORDINATE (DATIVE COVALENT) BONDING e from the same species. - Ofter drawn with, not showing the direction in which the electrons were donated A bond where both of the electrons come! - However, once formes, co-ordinate bonds are identical to other covalent bonds WHEN ARE COORDINATE BONDS POSSIBLE? - When there is an atom that has a pair of elections initi LONE PAIR outer shell, which are e not already revolved in CAN H₂O FORM A COORDINATE BONO WITH AH'ION H₂O O OTHERATON H ELECTRON) TOTAL ELECTRONS Ex CENTRAL ATOM ELECTRON ELECTRON PAIRS BONDING PAIRS LONE PAIRS WHICH ATOM CAN DONATE! EQUATION 1:3 bonding 2 ways of showing pours H-00 I H EXPLANATION - The 6 2 8 4 2 2 Oxygen + H' Because inc LONE PAIRS ON NONCENTRAL ATOMY ALC₁₂ + Cr² bending- 'n group 6 Because each H dongles ! Because 2 Hs to bond H +J in the H₂ O molecule has 2 lone pairs of elections, H₂0¹ • oxygen one of which it can donate to the H² ion •forming AICI, Al 3 CL 3 TOTAL 6 PAIRS 3 OP 3 0 LP diamond GIANT COVALENT STRUCTURES Grant cevalent structures form when the bonds between a grant lattice is formed atoms continue indefinitely, and a NEED TO KNOW! CL-AI CL I love your coming S. MELTING + BOILING POINTS B 5.0₂ ELECTRICAL CONDUCTIVITY - Does not conduct CI NEED TO KNOW - Generally very high L • many strong covalent beads must be broken - 1 required to overcome the bonding OTHER PHYSICAL PROPERTIES I LAYER GRAMENE metals can occassenally form. Dot-cross diagram ore weful formuadiria to no free ions /delocalued e's to move through structure + DIAMONO bube form man Pos LAYERS GRAPHITE -likefoongy - as covalent bends are strong - directional, they are - diamond is the hardest substance known to man - drills, glass cuthing de CIANT COVALENT LAYERED SUBSTANCES • stoveture + (ally change Substance containing • infinite lattice of covalently bonde d atoms in 2. dimensions only to form layers. > y are hard, strong-brittle Each C atom bonded to 3 others · Spore electronis delocalized, occupies space between lager ELECTRICAL CONDUCTIVITVI - Very good conductor of electricity delocalised electrons in each plane, free to move t and carry the charge DENSITY 1.3 ↳ Used in - Much less dense than diamond, due to large distances between planes. HARDNESS bonding - Soft, as planes can slip over each other due to weate intermolecules forces + as an industrial lubricant • pencils + to overcome e through structure HIGH M&A POINTE -mony strong covalent bonds must be broker-Ich of energy required o the bonding SIMPLE MOLECULAR STRUCTURES MELTING GBOILING POINTS - Generally low -Tu I wo or more alom, covalently bonded together. The bonds strong covalent bonds within the molecule are - These molecules are held together by intermolecular forces. (weaker than covalent, but strong enough to keep substance soted / tid (liquid) B.G. HYDROGEN ₂ covalent bonds intermolecular forces Hydrogen atom, intermolecular forces are weak intermolecular forces also decrease re increasing e rapidly with distance (ofter little difference between melking and boiling points) ELECTRICAL CONDUCTIVITY - Little electrical conductivity in either selid /liquid state 4 no 100s or delocalised electrons OTHER PHYSICAL PROPERTIES Weak intermolecular hores (non-disectioral) weak, soft, crumbly METALLIC BONDING - electrostatic force of attraction between + metalions and delocalized election 1.3.3 METALLIC BOADING MELTING & BOILING POINTS - Generally quite high - strong attraction between × 10-3 & delucolied ↳ Depends on strength of metallic bonds MALLEABLE & DUCTIVE -Can be hammered into shape and pulled out into wires. 4 Also sonorous & shing. ELECTRICAL CONDUCTOns → Delocalised oute shell elections are free to the structure and carry the charge STRENGTH OF METALLIC BONDS IONTE the -↑ protons stronger bond - More delocalised e's per atom stronger bond 4 outer shell elections are delocalised -4 - 4 types of cogital structure crystal METALLIC - Smaller the ion, stronger bond uelon, become smaller, the higher charge they a -ion is smaller /higher charged <- it can attract the de localiond e's molestrand 13.4 BONDING & PHYSICAL PROPERTIES GIANI COVAL ENT f MOLECULAR Sodium sodium chloride magnesium diamond graphite ile move iodine. throughout 135 SHADES OF SIMPLE MOLECULESIONS Molecules and roas poses 2 types of election pours BONDING PAIRS (2e stored in a covalent bond) LONE PAIRS (20- in a pair not involved in These electron pairs will repel each other as Lone pairs repel me I more than bonding pairs I با WEAKEST compact and sit close to the nucleus of the central arom) ↳ This reduces the bond angles to a small extent (unually 2:5⁰) • Bond ongles exist between the 2 bonding pass of electors 18 ne pair - lone pair repulsion Work out nos of STRONGEST lone 2 ELECTRON PAIRS 2 BONDING PAIRS OLONE PAIRS LINEAR 180° Q111Q Q I 3 ELECTRON PAIRS 3 BONDING PAIRS OLONE PAIRS TRIGONAL PLANAR 120° G 4 ELECTRON PAIRS 4 BONDING PAIRS OLP TETRAMEDRAL 109.5" Q A pair - bond poir repulsion G A 1.3 bonding Q 1- bord pair repulsion bonding & lone poss as in coordinate bending Q in bending- · for as possible. (becaux 3 BONDING PAIRS TRIGONAL PYRAMIDAL 107° 2 BONDING PAIRS BENT (V-SHAPE) 118 А ILP • they are. A more I LONE PAIP Q 2 BONDING PAIRS 2LP BENT (V-SHAPE) 106.5° 01111 4 5 BONDING PAIRS CLP TRIGONAL BIRVRANIDAS 120° 0° Q SELECTRON PAIRS EG Q C Le 1040 Q 4 pails 4bp Olp A1Q 0 O Q 6 ELECTRON PAIRS; 6 BONDING PAIRS OLP 5 BONDING PAIRS ILP OF TA HEORAL DISTO0100 UTANBORAL 90° 4 GONDING PAIRS ILP TRICONAL PYRAMIDAL Q 0 11 altr SEE-SAW Q AQ TRICONAL PLANAR Q DOUBLE BONDS - Generally and there are multiple 0 atom, in the molecule NON CHARGED MOLECULE CHARGED MOLECULE CO₂ that only made single words - this change goes on Omilemley C GROUP O GROUP 4 bonding pairs are in 2 double bonds bending with 0 4• in bonding with C, us bx² BONDING PAIRS ILP BRILONAL PANAP 120° seem to occur when O is not the centralatom, 0 xo Q C O T-SHAPE 59² A Q BONDING PAIRS 2 LP SQUARE PLANAR 90° Q 0=0=0 ELECTRONEGATIVITY - the power of an I an atom to attract e pair of elections in a covolent kind the ELECTRONEGATIVE - SCALE 0-4 ELECTROPOSITIVE-atom with low electroned 0-10 - alom with high electronegalbrity } s electronegativity So GROUP s - cannot be described as electronegative, as they don't tend to form covalent bonds FLUORINE - electione one gativity value of 4.01 FACTORS AFFECTING ELECTRONEGATIVITY 。 (highest) NUCLEAR CHARGE TNC TEN 13.6 BOND POLARITY TAR VEN ATOMIC RADIO 15 LEN Increasing nudes charge, (increasing proten. proton no.), • Stronger attraction between nuclews + bonding pare of electroni SHIELDING - Increasing atomic radio, oute elections further from moulens 4 Weakes attraction between nucleus and bonding pair of electrons TREND IN ELECTRONEGATIVITY 1.3 bonding increasing - Increasing shielding. (more election shells). repulsion of outer elections by elections in inner shells 4 Weaker attraction between nucleus and bonding. pair of elections ACROSS A PERIOD Electronegativity i increases NC↑ SARS * more attrache, between nucleus and bending pair of electrons DOWN A GROUP Electronegativity. ART, ST 4 less attraction betwees nucleus and boiding pair of elections. decreases INTERMEDIATE BONDING - lonic + covalent bonding are the extremes of a continuam of bonding type 4 Differences in dectio negativity a • compound lies on this scale COVALENT BONDING • compounds containing elements of similar electione gebrity ↳s As they have a small electronegabuity diffince - quietley comodat CONIC BONDING • compounds containing elements of very different electronegathnily ↳ As they have a large see tronegativity difference (21-7) - conse POLAR COVALENT BOND (PERMANENT DIPOLED - elements in the bond have different electronegativities (03-17) - there is an unequal distribution of electrons in the bond ↳ Produces a charge suparation; dipole ends (6+ 6-) • The element with the larger electronegativity! polar compound will be the election rich (5-) and ↳ The element with the smaller electronegativity in c poter compound will be the electron deficient (5+) end in D a 4 can attract lone pairs of elections E.G S+ H + can determine where 8- CL Show direction of electron morat SYMMETRICAL MOLECULES POLAR & NON POLAR MOLECULES CI shared e cloud uneven distribution of electron density around molecule molecule (ALL BONOS IDENTICAL - A ·symmetrical LONE PAIRS) will be non-polar, even if individual bonds within the molecule are e polar The individual dipoles on the benas "cancel out", due to the symmetry of the molecule. NO NET DIRBLE MOVEMENT - NON-POLAR MOLECULE & NO 13-7 FORCES BETWEEN MOLECULES INDUCED DIPOLE-DIPOLE FORCES (VANDER WAALS / LONDEN DISPERSION) - Weakest of all intermolecular forces Present in all molecular substances HOW INDUCED D-D FORCES FORM - Electrons are constantly moving in a molecule which induces a temporary dipote - This induces a temporary dipole in a neighbouring molecule The 8- end of the dipole in one molecule, and the 8+ end of the dipole. a neighbouring molecule in attract each other FACTORS AFFECTING STRENGTH OF INDUCED ORD FORCES - ↑ size /sA of molecule, ↑ strength of • ↑otrength of • - ↑ number of election, T PERMANENT DIPOLE - DIPOLE FORCES 1/100 - Approximately - Present only in polar molecules HOW PERMANENT D-D FORCES FORM - There are polos molecules 8. 1.3 bonding S- 10.0 S+ strength of a covalent bond e permanent dipole - dipole attractions between S- directly impacts M&B prints /NOT in non- pelos molecules H-CL---H-CI 1 COVALENT INTERMOLECULAR PERMANENT ADNO FORCE MUST BE LINEAR HYDROCEN BONDING - Strangest of all intermolecular forces //10 to Approximately Vio strength of a covalent bond - Special case of permanent dipole-dipole attractions is Hatom is bonded to a very electronegative atom (N/0/F) - It is a strong intermolecular force (not a bond) lymatrate with - Common examples - HF, H₂O, NH₂ amino acid) -alcohols, carboxylic ass Acids GAES HOW HYDROGEN BONDS FORM There: s a very large values of H and N/0/5 lorge difference between the electronegativity · Hydrogen becomes. electron •deficient (5+) and ~/0/F becomes very election rich (8-) · very e - The 8+ Hydrogen atom forms an attraction with a lone pair of elections on N/0/F NH₂ H in the neil non-polar induced dipole-dipote he neighbowing mostrenade THE H-NO-H-NO MONT BELINEAR ---H-NO H COMPARING MELTING AND BOILING POINTS. WHAT TYPE OF INTERMOLECULAR FORCES? Is the molecule pola/non pol ↓ permanent 0-0 polar doesit contain H-N/H-0/ HOF YES ↓ i booding WHICH INTERMOLECULAR FORCES TO COMPARE Induced 0-10$ Induced 0-0 Induced 0-0 & Permanent 0-0 induced 0-0 & Hydroge bonding Permanent 0.0 & Hydrogen bonding Never compare strengths of 2 mccules with wody /20-0 EXAMPLE PARAGRAPH - F₁ & MP The H-bonding forces of attraction between the HE molecules IF COMPARING INDUCED D-D because the are stronger than the Induced D-D forces of attraction between the 51 molecules _molecule hova greak size /sn then the __) - These forces of attraction require more energ therefore He has a higher boiling point to overcome f