Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
57 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
What kind of structure does a metal have |
Giant metallic structure |
|
|
|
Metallic bonding definition |
" is the strong electrostatic attraction between the lattice of positive ions and the sea of delocalised electrons. |
|
|
|
Factors of the strength of metallic bond |
1. Number of valence electrons 2. Charge density |
|
|
|
Formula if charge density |
Charge density = kcharge/radius |
|
|
|
How does no. of valence electrons affect metallic bond? |
↑ Valence electrons contributed to the sea of deloc electrons, ↑ strength of metallic bond |
|
|
|
How charge density affect metallic bond? |
↑ charge density, ↑ metallic bond |
|
|
|
Properties of metals |
High mp np Good conductors of electricity " Heat Malleable and ductile |
|
|
|
Why do metals have high mp bo? |
Large amount of energy required to overcome strong electrostatic foa between lattice of.. sea of.... |
|
|
|
Why are metals good coductors of electricity |
When a potential difference is apploed, the delocalised mobile electrons flow towards positive potential. |
|
|
|
Why are metals good conductors of heat |
Heat→KE Delocalised mobile electrons transmit the kinetic energy to other parts of metal |
|
|
|
Why are metals malleable and ductile? |
Metallic bonds are non-directional. Layers of metallic cations can slide over one another without breaking the metallic bond. |
|
|
|
Alloy definition |
Mixture of metals or metals and non-metals |
|
|
|
Why are alloys hard, strong and not malleable? |
Foreign metal cation of a different size disrupts the orderly arrangement or the cations of the pure metal. |
|
|
|
What kind of structures do ionic compounds have? |
Giant ionic structures. |
|
|
|
How is an ionic bond formed |
Through the complete transfer of electrons from a highly electropositive atom to a highly electronegative atom. Cations and Anions are formed. |
|
|
|
Definition of ionic bond |
" refers to the electrostatic attraction between the oppositely charged ions |
|
|
|
Factors affecting strength of ionic bond |
1. Charges of ion 2. Ionic radius |
|
|
|
Lattice energy definition |
" is the the result of electrostatic foa between the oppositely charged ions in an ionic compound |
|
|
|
Formula of magnitude of lattice energy |
|Lattice energy, 🔼Hlatt(theta)|=k|(q+q-)/(r++r-) |
|
|
|
How does lattice energy affect ionic bond? |
Larger magnitude of LE= Stronger ionic bond |
|
|
|
Properties of ionic compounds |
1. High mp bp 2. Non-conductors of electricity in solid state, conductors in molten or aq state 3. Soluble in polar solvents 4. Insoluble in non-polar solvents 5. Hard and brittle |
There are 5 properties |
|
|
Why does ionic compounds have high mp dp |
Large amount of energy required to overcome the strong electrostatice foa between oppositely charged ions |
|
|
|
Why do ionic compounds conduct electricity in aq or l state but not s state |
In s state, ions vibrate about fixed positions. No mobile charge carriers. In l or aq state, free mobile charge carriers. |
|
|
|
Why are ionic compounds soluble in polar solvents |
Each ion on the crystals surface attract oppositely charged parts of the polar solvent molecules. The ions form ion-dipole interactions with the solvent and become hydrated. The formation of ion-dipole interaction is exothermic enough to overcome the strong electrostatic foa between opp charged ions |
|
|
|
Why are ionic compounds insoluble in non-polar solvents |
It cannot form compatible bonds with the solvent. Solute-solvent interaction is not exo enouvh to overcome tje strong electrostatic foa between oppositely charged ions. |
|
|
|
Why are ionic compounds hard and brittle? |
Hard Every ion is held by strong ekectrostatic forces of attraction between oppositely charged ions. Large amount of energy to over come electrostat attractions. Brittle Sharp blow brings ions of like charges together→strong electrostatic repulsion→shatters the giant ionic lattice |
|
|
|
Covalent bond definition |
Covalent bond is the electrostatic attraction between the two positive nuclei and the shared pair of electrons |
|
|
|
What structure does covalent molecules have |
Simple molecular structure or giant covant structure |
|
|
|
Factors affecting covalent bond |
1. Bond length 2. Bond energy 3. No. of bonding electron |
|
|
|
How does bond length affect covalent bond |
The shorter the bond length, the stronger the attraction befaeen the nuclei and shared electrons, bond strength ↑ |
|
|
|
Definiton of bond length |
" the distance between the nuclei of the two atoms joined by the covalent bond |
|
|
|
Bond energy definition |
" is the amount of energy that is needed to break one mole of the covalent bond in a gaseous molecule into constituent gaseous atoms. |
|
|
|
How does bond energy affect strength of covalent bond? |
Higher bind energy, stronger bond |
|
|
|
What are the types of covalent bonds? |
Sigma bonds and pi bonds |
|
|
|
How are sigma bonds formed and where is the electron density |
When orbitals of two atoms overlap head on. Electron density is concentrated between nuclei of the two bonding atoms |
|
|
|
State the types of sigma bonds |
1. Two s orbitals overlap 2. Two p orbitals overlap 3. One s and one p orbital overlap |
|
|
|
State the type of pi bonds |
1. Two p orbitals overlap sideways |
|
|
|
Is a sigma bond stronger than a pi bond? |
Yes |
|
|
|
Why is the sigma bond stronger than the pi bond |
The overlapping of orbitals is more effective than that of a pi bond. |
|
|
|
How is a dative bond formed? |
" by one atom donating a lone pairand sharing a pair of electrons with another atom which has a vacant orbital |
|
|
|
Conditions for a dative bond |
1.Donor must have at least a lone pair of electrons 2. Acceptor must have a vacant orbital 3. Symbol → is used to denote a dative bond 4. Addition product is formed. |
|
|
|
Steps to drawing dot and cross diagram |
1. Draw the skeleton structure. Central atom is least EN 2. Add electrons to the more EN element 3. Remove electron from less EN element. 4. Try dative bonds if valence electron exceed 8 for perio 2 . |
|
|
|
Trend of EN across PT and down PT |
Increases, decreases |
|
|
|
Why is expansion of octect only possible for period 3 onwards? |
They have energetically accessible 3d orbitals for bonding. Period 1 and 2 have no available d orbitals. |
|
|
|
Why is expansion octet limited by both the size of the central atom and its terminal atoms? |
If the terminal or central atom has a larger size, there is a greater repulsion between the Cl atoms at the octahedral corners, steric hindrance exist. |
|
|
|
Octet rule states that... |
the central atom is surrounded by eight electrons |
|
|
|
How to draw a lewis structure |
1. Single bond or a shared pair of electrons is denoted by a straight line 2. Lone pairs of electrons on the central and surrounding atoms havr to be shown as ⚫⚫ not ✖✖ 3. Shape of the molecule must be clearly shown |
|
|
|
The shape of a molecule is determined by... |
the repulsion between electron (bond and lone pairs) pairs around the central atom. |
|
|
|
Rules for applying VSEPR theory |
1. Identify the central atom. 3. Electron pairs around the central atom are arranged as far apart as possible so as to minimise repulsion 3. Lone pairs exert a bigger repulsion than bond pairs because they occupy a bigger volume of space. 4. Repulsion between bond pairs increases with EN of central atom because electron pairs are closer to the nucleus |
|
|
|
Order of strength of electron repulsion |
Lone pair-lone pair> lone pair-bond pair> bond pair-bond pair |
|
|
|
What types of bonds are counted as bond pais |
Single, double, triple and dative |
|
|
|
State the basic shape with 2 electron pairs and its bond angle |
Linear, 180 |
|
|
|
State the basic shape and other actual shape with 3 electron pairs and its bond angle |
Trigonal planar, 120 Bent shape, <120 |
|
|
|
State the basic shape and other actual shapes with 4 electron pairs and its bond angle |
Tetrahedral, 109.5 Trigonal pyramidal, 107 Bent 105 |
|
|
|
State the basic shape and other actual shape with 5 electron pairs and its bond angle |
Trigonal bipyramidal 120 equi, 90axial Distorted tetrahedral - T shaped <90 Linear 180 |
|
|
|
State the basic shape and other actual shape with 6 electron pairs and its bond angle |
Octahedral,90 Square pyramidal, <90 Square planar. <90 |
|
|
|
Format for answering VSEPR questions |
1. State numer of electron regions around central atom including bond pairs and lone pairs 2. To minimise repulsion, the electron pairs are directed to Opposite sides of each other (2) Corners of a equilateral triangle 3 Corners of a regular tetrahedron 4 Corners of a regular trigonal bipyramidal 5 Corners of a octahedron 6 3. State shape of molecule 4. 1 lone pair on central atom Lplp>bpbp repulsion 2 lone pair on c.a. Lplp>lpbp>bpbp 5. Bond angle is compressed to... hence the molecule has a ... shape |
|
