Unit 1 - Atomic Structure and the Periodic Table (9CH0)
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Summary - Unit 1 - Atomic Structure and the Periodic Table (9CH0)
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Unit 1 - Atomic Structure and the Periodic Table (9CH0)
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PEARSON (PEARSON)
A summary of topic 1, organised so the notes are easy to understand. The notes are on slides, so they can be printed out and used as revision cards or posters, for revision on the go. The notes cross-reference the specification so it is easy to see where each bit of information has come from. They ...
Unit 1 - Atomic Structure and the Periodic Table (9CH0)
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Relative atomic mass Isoelectronic = atoms/ions w/ same electronic configuration
= the average mass of an atom of an element (in its natural Ionisation energy
abundance) relative to 1/12th of the mass of an atom of C-12 1st = the energy needed to remove 1e- from every atom in a
- Average of all isotopes using % abundance mole gaseous atoms
- Ar = ∑(mass x abundance) X(g) → X+(g) + e-
Total abundance 2nd = the energy needed to remove a second e- from every atom
Relative isotopic mass in a mole of gaseous atoms after the 1st e- has been removed.
= the average mass of an atom of an isotope realtve to 2nd IE >1st IE because 1+ ion has a smaller ionic radii ∴ harder
1/12th of the mass of an atom of C-12 to remove 2nd e-
- Different isotopes have different masses due to X+(g) → X^2+(g) + e-
different numbers of neutrons Things that affect energy required to remove e-:
Relative molecular mass - Distance from nucleus (radii)
= the average mass of a molecule relative to 1/12th of the - Nuclear charge
mass of an atom of C-12 - shielding
- Add up all the atomic masses of elements in a Slow ↓ in 1st IE down the group
molecule (higher number on periodic table) Rapid ↑ in 1st IE across a period
- Mr = NaCl Between groups 2&3:
Na = 23 Group 3 1st IE lower than group 2
Cl = 35.5 = 23+35.5=58.5 Because outer electrons in 2p orbital rather than 2s
Relative formula mass - 2p = ↑ shielding & ↑ distance from the nucleus
= the relative molecular mass for a compound that is not a Between groups 5&6:
molecule e.g. ionic compounds (giant structures) Group 6 1st IE lower than group 5
Mass spectrometry The repulsive forces between the
Ionisation, acceleration, deflection, detection electrons in the same orbital makes
We can use mass spectrum & Ar equation the extra e- easier to lose
M+ peak = Mr of molecule Periodicity:
Atomic emission spectra: = a regular repeating pattern/trend of atomic, physical or
E- jumps energy levels, then loose the energy in specific chemical properties across a period.
frequencies → shows there’s fixed energy levels. Atomic radius: Across a period = atomic radii ↓
Orbitals = holds 2e- Down a group = atomic radii ↑
- S = 1 orbital, spherical Melting point: Group 1-3 = increasing (metallic bonding)
- P = 3 orbitals Group 4 = highest MPT (giant lattice covalent)
- D = 5 orbitals Group 5-7 = low MPT (simple covalent)
- F = 7 orbitals 4s filled before 3d, 3d emptied before 4s Group 8 = low MPT (monoatomic)
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