UNIT 1 CHEMISTRY
- Created by: Meleka
- Created on: 03-12-19 15:48
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- Chemistry
- Bonding
- Ionic
- When an atom of an element loses one or more elections and gives it to another atom
- Atom that looses becomes positive, atom that gains become negative due to imbalance of protons and electrons
- Covalent
- Two non-metals forms when an electron is shared between the atoms
- Chemical bond that involves the sharing of electron pairs between atoms
- Metalic
- Not as strong as covalent and ionic
- Electrons in the highest energy level of the metal atom has the ability to become delocalised- free to move around
- Hydrogen
- Electrostatic forces of attractions between molecules which cotain these highly polar bonds which can be classified as the strongest form of intermolecular forces.
- Ionic
- Metals
- High melting points, malleable, ductile, electrical/ thermal conductors and solid at room temp
- Forces
- Intermolecular
- How chemical substances behave, attraction and repulsion between particles
- London
- Weakest intermolecular force. Temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form a temporary dipoles.
- Van der waals
- Defined as intermolecular attractions
- Intermolecular
- Properties of elements
- Electronegativity
- Tendency of a atom to attract a bonding pair of electrons. Decreases as you go down a group and increases as you go across a period
- Across the period, bonding pair of electrons will be shielded by the same number of electrons but the protons will increase
- Down a group, more shielding from inner electrons and the bonding pair of electrons are further away from the nucleus. Adds up less pull from the bonding pair from positive charge of the nucleus this decreases the electronegativity
- First ionisation energy
- Energy needed for one mole of electrons to be removed from one mole of gaseous atom
- Decreases going down group, electron to be removed from the outer energy level is increasing distant from the nucleus result of the atom getting bigger
- Increases across a period, more atoms re being added to the nuclei of the atoms increase in nuclear charge. Electrons in outer energy levels will be more tightly held, and more difficult to move
- Electron affinity
- Change in energy when one mole of gaseous atom gains one mole of electrons to form one mole of negative ion
- Increases from left to right across periods, electrons added to energy level becomes closer to the nucleus a stronger attraction between the nucleus and its electron
- Decreases down a group, electrons are placed in a higher energy level far from the nucleus decrease from its pull
- Electronegativity
- Patterns in periodic table
- Melting and boiling points
- Depend on the strength of forces which exist between the particles which makes up a substance
- Vary in regular way or pattern depending on their position in the periodic table
- Group 1 elements decrease on descending the group due to decrease in the forces of attraction between the atom
- Crossing a period
- Electrons in outer energy level are attracted more strongly so are pulled closer to the nucleus resulting in the atomic size to decrease
- Descending a group
- One element to the next the number of occupied energy levels is increasing. Resulting in atomic size to increase
- Melting and boiling points
- Bonding
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