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)
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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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