Periodicity Flashcards

1
Q

covalent radii definition

A

half the distance between the nuclei of two covalently bonded atoms.

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2
Q

covalent radii trend across a period

A

decreases because the nuclear charge is increasing and so the electrons in the filled outer shells are pulled in closer to the nucleus.

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3
Q

covalent radii trend down a group

A

increases because the number of electron shells is increasing so atomic size increases.

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4
Q

first ionisation energy definition

A

the energy required to remove one mole of electrons from one mole of gaseous atoms.

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5
Q

second ionisation energy definition

A

the energy required to remove one mole of electrons from one mole of gaseous 1+ ions.

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6
Q

ionisation energy trend across a period

A

increases because the nuclear charge is increasing and so the electrons are more strongly attracted to the nucleus resulting in more energy required to remove an electron.

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7
Q

ionisation energy trend down a group

A

decreases because an electron is being removed from an electron shell which is further from the nucleus. (weaker electrostatic attraction)
the inner shells of electrons ‘shield’ the outer electrons from the nuclear charge meaning they are less strongly attracted to the nucleus resulting in less energy being required to remove an electron.

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8
Q

electronegativity definition

A

a measure of the attraction an atom involved in a bond has for the electrons in the bond.

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9
Q

electronegativity trend across a period

A

increases as nuclear charge is also increasing in this direction which creates a stronger electrostatic attraction between the nucleus and the negative bonded electrons.

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10
Q

electronegativity trend down a group

A

decreases because the atomic size increases due to the increases number of electron shells. The increase in shells of electrons ‘shield’ the bonded electrons from the nuclear charge meaning they are less strongly attracted to the atoms.

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11
Q

screening effect

A

when inner electrons shield an outer electron from the attractive effect of the nucleus and less energy is needed to remove the outer electrons as a result.

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12
Q

the periodic table

A
  • invented by Dimitri Mendeleev in 1869
  • elements arranged in order of increasing atomic number
  • mp, bp and density are periodic in nature
  • elements in the same group have similar chemical properties
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13
Q

why does it require much more energy to remove an electron from a full electron shell?

A
  • destroys the stability associated with the full arrangement of electrons.
  • electron is closer to the nucleus (more strongly attracted)
  • harder to remove an electron from a positive ion than an atom.
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14
Q

buzz words that should make you think of electronegativity in exam

A

“attraction for bonding electrons”

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15
Q

group in periodic table

A
  • vertical columns
  • similar chemical properties
  • common number of electrons in outer shell
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16
Q

period in periodic table

A
  • horizontal rows
  • increasing atomic number
  • increasing number of electrons in outer shell
  • move from metallic to non-metallic characteristics