7890972
Description
Flashcards by Anushka John, updated more than 1 year ago
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Created by Anushka John
over 7 years ago
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| Question | Answer |
| Define ionic bonding | An ionic bond is the electrostatic force of attraction between oppositely charged ion formed by electron transfer |
| Give the formula of the sulphate ion | |
| Give the formula of the hydroxide ion | |
| Give the formula of the nitrate ion | |
| Give the formula of the carbonate ion | |
| Give the formula of the ammonium ion | |
| Write out the electronic structure of Mg and Mg2+ | Mg goes from 1s2 2s2 2p63s2 to Mg2+ 1s2 2s2 2p6 |
| Write out the electronic structure of O and O2- | O goes from 1s2 2s2 2p4 to O2- 1s2 2s2 2p6 |
| When is ionic bonding strongest? | When the atom is 1) Smaller 2) Greater charge |
| Define a covalent bond | A single covalent bond is a shared pair of electrons |
| What are multiple covalent bonds? | Multiple pairs of shard electrons |
| What is a dative covalent bond | A shared pair of electrons where both of them are from the same atom |
| What are three common examples of compounds containing dative covalent bonds? | H3O+ , NH4+ and NH3BH3 |
| Show how NH3BH3 is formed | |
| A dative covalent bond is shown using an... | arrow |
| Define a metallic bond | The electrostatic forced of attraction between positive metal ions and and the sea of delocalised electrons |
| What 3 factors determine the strength of a metallic bond? | 1) The number of protons (more = more attraction) 2) Number of delocalised electrons per atom (more = more attraction) 3) Size of the atom (smaller = stronger attraction) |
| Why does Mg have a higher melting point than Na? | *Mg has stronger metallic bonding than Na and hence a higher melting point. *The Metallic bonding gets stronger because in Mg there are more electrons in the outer shell that are released to the sea of electrons. *The Mg ion is also smaller and has one more proton. There is therefore a stronger electrostatic attraction between the positive metal ions and the delocalised electrons and higher energy is needed to break bonds. |
| What are the four types of crystal structure? | 1) Ionic 2) Macromolecular (Gaint covalent) 3) Metallic 4) Molecular |
| Name the name and angle of the shape for 2 bp and 0 lp | linear, 180 |
| name and angle for 3 bp and 0 lp | trigonal planar, 120 |
| name and angle for 3 bp and 1 lp | trigonal pyramidal, 107 |
| name and angle for 4 bp and 0 lp | tetrahedal, 109.5 |
| name and angle for 2 bp and 2 lp | bent, 104.5 |
| name and angle for 5 bp and 0 lp | trigonal bupyramidal , 120 and 90 |
| name and angle for 6 bp and 0 lp | octahedral, 90 |
| give an example of a linear molecule | CO2, CS2 , HCN, BeF2 |
| example of a trigonal planar | BF3 , AlCl3 , SO3 , NO3^-, CO3^2- |
| example of a tetrahedral | SiCl4, CH4, NH4+ |
| example of trigonal pyramidal | NH3, NCl3, PF3, ClO3 |
| example of bent | H2O, Cl2O, H2S |
| example of trigonal bipyrramidal | PF5, PCl5 |
| THE example of octahedral | SF6 |
| Define electronegativity | The power of an atom to attract the pair of electrons in A COVALENT bond towards itself |
| Which are the most electronegative elements? | N, O, F |
| What happens to electronegativity as you go along a period? | Increases as number of protons increases and no increase in shielding so outer electrons shells are pulled in more -> decrease in atomic radius |
| What happens to electronegativity as you go down a group? | Decreases as atoms get larger so distance between nucleus and outer electrons increases and the shielding effect due to inner electrons increases |
| What is a polar covalent bond? | When electron distribution in a covalent bond is unequal due to differences in electronegativites between the different element sharing the electrons. |
| What does a polar covalent bond cause a molecule to have? | A permanent dipole |
| Why are some molecules, which contain polar bonds within it, not a permanent dipole? | Because they are symmetrical so the individual dipoles cancel each other out so there is no NET dipole moment, the molecule is NON POLAR |
| What types of substances do van der Waals occur in? | All molecular substances and noble gases but NOT in ionic substances |
| Why do van der Waals occur? | Because electron density in a molecule is constantly moving randomly, so some parts become more negative than others, ie a small temporary dipole. This then induces dipoles in neighbouring molecules. |
| What is the main factor affecting the size of the van der Waals? | the size of the molecules. Bigger molecule = more electron = more likely for a dipole to form = stronger van der Waals = higher boiling points |
| Why does the boiling point of halogens increase as you go down the group? | Molecules get bigger = more electrons = more van der Waals = higher bp (this is why Cl2 is a gas and I2 is a solid) |
| How does shape of a molecule affect the size of the van der Waals? | Long chain alkanes have a larger surface area of contact between molecules for van der waals to form than compared to spherical shaped branched alkanes and so have stronger van der waals |
| When do permanent dipole-dipole forces occur? | Between polar molecules. Polar molecules have a permanent dipole and are asymmetrical and have a bond where there is a significant difference in electronegativities |
| When does a hydrogen bond occur? | When H is attached to one of the three most electronegative elements (NOF) and this electronegative atom must have an available lone pair. {remember to include lone pairs on diagrams} |
| Explain the trend and anomalies in the boiling points of the various hydrides | The anomalously high boiling points of H2O, NH3 and HF are caused by the hydrogen bonding between the molecules The general increase in boiling point from H2S to H2Te is caused by increasing van der Waals forces between molecules due to an increasing number of electrons. |
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