Periodicity

• How are elements arranged in the periodic table?

  By proton number
• What do the groups in the periodic table represent?

  Columns where elements have the same number of electrons in their outer shell
• How many electrons do group one elements have in their outer shell?

  One electron
• What happens to the reactivity of group one elements when moving down the group?

  They react with increasing vigor
• What do periods in the periodic table represent?

  Rows where elements have the same number of electron shells
• What is the trend in atomic radius as you go across period 3?

  The atomic radius decreases
• Why does the atomic radius decrease across a period?

  Due to increased nuclear charge pulling electrons closer to the nucleus
• What is the shielding effect in atomic structure?

  The protection of inner electron shells from the nucleus
• What happens to atomic radius as you go down a group?

  The atomic radius increases
• What is the reason for the increase in atomic radius down a group?

  Extra electron shells are added
• Which elements in period three are metals?

  Sodium, magnesium, and aluminium
• What type of bonding do sodium, magnesium, and aluminium exhibit?

  Metallic bonding
• Why does magnesium have a higher melting point than sodium?

  Magnesium has a greater positive charge and more delocalized electrons
• What type of structure does silicon have?

  A giant covalent structure
• What is the formula for phosphorus?

  P4
• What determines the melting point of phosphorus?


  Weak van der Waals forces
• Why does sulfur have a higher melting point than phosphorus?

  Because sulfur (S8) has larger van der Waals forces due to being a bigger molecule
• What is the formula for sulfur?

  S8
• Why does chlorine have a lower melting point than sulfur?

  Chlorine (Cl2) is a smaller molecule with weaker van der Waals forces
• What type of structure does argon have?

  Monoatomic structure
• What is ionization energy?

  The minimum amount of energy required to remove one mole of electrons from one mole of atoms in the gaseous state
• What is the first ionization energy of sodium?

  495.8 kJ/mol
• Why is ionization energy considered an endothermic process?

  Because energy is required to remove an electron from an atom
• How does shielding affect ionization energy?

  More electron shells between the nucleus and the outer electron reduce the attraction, requiring less energy to remove the electron
• Why is atomic size important in relation to ionization energy?

  Bigger atoms have a greater distance between the nucleus and the outer electron
• Why are keywords important in chemistry?

  Keywords help in accurately describing concepts and processes
• What trend is observed in the melting points of elements in period three?

  There is a general increase in melting points among metals, followed by a decrease for non-metals
• How does structure relate to melting point in elements?

  Stronger bonds and larger structures generally lead to higher melting points
• What type of bonds are present in silicon's structure?

  Covalent bonds
• What role do delocalized electrons play in metallic bonding?

  They contribute to the strength of the metallic bond by allowing for greater electrostatic attraction
• What is the symbol for sodium when it loses an electron?

  Na+
• What is the first ionization energy of sodium in KJ per mole?

  495.8 KJ per mole
• Why is energy required for ionization?

  Because an electron is being removed from an atom
• What type of process is ionization considered to be?

  Endothermic process
• What does shielding refer to in atomic structure?

  The protection of outer electrons from the nucleus by inner electron shells
• How does the number of electron shells affect the energy required for ionization?

  More shells result in less energy required due to weaker attraction
• What happens to atomic size as you move down a group?

  Atomic size increases
• Why do larger atoms lose electrons more readily?

  Because the distance between the nucleus and outer electrons is greater
• What is the relationship between nuclear charge and ionization energy?

  A higher nuclear charge generally increases the energy required to remove an electron
• How does shielding impact ionization energy as you go down a group?

  Shielding has a greater impact than nuclear charge, making ionization easier