Periodicity I
Which direction does atomic radius generally increase in the periodic table?
Down a group and toward the left across a period.
What type of bond forms when electrons are transferred between atoms?
Ionic bond.
Which group contains the noble gases?
Group 18
What bond is found in H₂?
Covalent bond.
This bond forms between a metal and a non-metal because of a large difference in electronegativity.
Ionic bond
Why does atomic radius decrease across a period?
Increasing nuclear charge pulls electrons closer to the nucleus.
Why are metals good conductors of electricity?
They contain mobile delocalized electrons.
What periodic trend explains why fluorine is highly reactive?
High electronegativity and strong attraction for electrons.
What happens to atoms when a covalent bond forms?
They share electrons to achieve stability.
What is 2nd ionization energy?
The minimum amount of energy required to remove 1 mole of electrons from one mole of gaseous singly charged positive ions (1⁺ ions) to form gaseous doubly charged positive ions (2⁺ ions).
Arrange the following in order of increasing electronegativity:
C < N < O
Identify the bonding type in CH₄
Covalent
Why do noble gases generally have very high ionization energies?
They possess stable filled valence shells
Determine the bonding in Al₂O₃
Predominantly ionic.
Arrange the following in increasing covalency. BCl3, NCl3, BeCl2
BeCl2, BCl3, NCl3
Explain why chlorine has a higher electron affinity than sodium.
Chlorine requires only one electron to achieve a stable octet.
Compare metallic bonding and ionic bonding.
Metallic bonding involves metal ions and delocalized electrons; ionic bonding involves attraction between oppositely charged ions.
Between Ca²⁺ and K⁺, which ion is smaller? and why?
Ca²⁺. The higher the positive charge, the stronger the attraction, and the smaller the ionic size
Why do ionic compounds dissolve in water?
Polar water molecules attract and separate ions.
Predict the type of bonding present in calcium fluoride (CaF₂) and explain why it has a higher melting point than potassium fluoride (KF)
Ionic. CaF₂ has stronger electrostatic attractions because calcium ions carry a 2+ charge, producing stronger ionic bonds than the 1+ charge in KF.
Which has the larger radius: O²⁻ or F⁻? and why?
O²⁻, because the more electrons are added to the valence shell, the lesser the nuclear attraction, hence the bigger the atomic size
A substance has a very high melting point, does not conduct electricity when solid, but conducts when molten. What type of bonding is present?
Ionic bonding.
Predict and justify which element has the highest ionization energy in Period 3.
Argon; it has a complete valence shell and high effective nuclear charge.
Explain why MgO has a higher melting point than NaCl.
Mg²⁺ and O²⁻ have higher charges, creating stronger electrostatic attractions.
Li2+ is isolectronic with H atom. Would you expect the ionization energy for Li2+ to be larger or smaller than that of H? Explain
Li2+ has 3 protons and H has only 1 proton. The greater the number of protons, the greater the nuclear charge and hence the greater inward pull of the electronic shells. More energy will therefore be required to remove an electron from Li2+ than in H.