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32 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the activation energy in a reaction? |
The activation energy is the amount of energy it takes to start a chemical reaction |
Think graphs |
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What is ionisation energy? |
The amount of energy it takes to remove one mole of electrons from one mole of atoms |
Think removing |
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What is an exothermic reaction? |
It is a reaction that gives out energy so the product(s) often have more energy than the reactant(s) |
Is it more or less energy than reactant? |
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Is delta H positive or negative for an exothermic reaction? |
Negative because products have less energy than the reactant. |
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Is delta H for an endothermic reaction positive or negative? |
Positive because reactants have less energy than the products. |
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What is an activated complex? |
The middle stage of a reaction. It has lots of energy. |
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What is a heterogeneous catalyst? |
When the reactants and catalyst are in different States |
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What is a homogeneous catalyst? |
When the reactants and catalyst are in the same state |
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What do catalysts do to the activation energy? |
They reduce/lower it |
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What happens to the number of energy levels as you go across a period? |
Stays the same |
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What happens to the size of atoms as you go across a period? |
It decreases |
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What are delocalised electrons? |
In metallic bonding, the electrons in the outershell tend to move from atom to atom. They don't belong to one atom. |
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What happens to the strength of metallic bonding as you go across a period? |
It increases because the positive core pulls electrons closer to the nucleus |
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What are london dispersion forces? |
Weak intermolecular bonds |
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What is a permanent dipole? |
When electrons in an atom become unevenly distributed |
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What is a fullerene? |
Covalent molecules that have a big formula. |
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What describes the shape of fullerenes? |
Football shaped or tube shaped |
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What are polymorphs? |
They are different forms of the same element. Like graphite and diamond. They are both made form carbon |
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What is the structure of a covalent network? |
A large lattice |
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What is the melting point and boiling points of covalent network elements? |
In the thousands (°c) |
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Why do covalent network elements have such a high melting and boiling points? |
Because you have to break every covalent bond in the lattice. |
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Why do ionic bonds have such high melting points? |
They have a crystal lattice structure contain many bonds and take up more energy to break |
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Why do covalent solids have low melting points? |
It's not the bonds that break in covalent bonds, it's the intermolecular bonds called london dispersion forces |
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What is electronegativity? |
Is the measure of how strong the attraction is between the nucleus and the electrons in an atom |
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What happens to electronegativity when you go along a period? |
It increases |
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What happens to electronegativity when we go down a group? |
It decreases |
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Why does electronegativity increase and what happens to the covalent radius? |
There are more electrons in the atom and the covalent radius gets smaller |
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Why does electronegativity decrease and what happens to the covalent radius? |
The covalent radius gets bigger because energy shells are added. Because of the increased number of shells, the attraction between the nucleus and the outermost electrons and electronegativity decreases. |
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What is polar covalent bonding? |
An unequal sharing of electrons |
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What is hydrogen bonding? |
•a permanent dipole-permentent dipole attraction • between hydrogen, nitrogen, oxygen and fluorine only |
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What is intermolecular bonding? |
Bonding between atoms not in them |
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What is an intramolecular bond? |
Within atoms not between them |
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