Grade 10 chemisty – Chemical Bonding Quiz
1. Which description best explains an ionic bond?
Ionic bonds form when one atom transfers electrons to another, producing oppositely charged ions that attract each other.
2. When is a bond most likely to be ionic based on electronegativity difference (EN)?
Large electronegativity differences (commonly >1.7) mean one atom attracts electrons much more and electron transfer (ionic bonding) is likely.
3. What is the oxidation state of magnesium in MgCl2?
Chloride ions are each -1, so two Cl- give -2 overall; magnesium must be +2 to balance, giving Mg2+.
4. Which property is typical of ionic solids like sodium chloride?
Ionic solids have strong electrostatic attractions (high melting points) and mobile ions only when molten or in solution, allowing conduction.
5. How is a covalent bond formed?
Covalent bonds involve atoms sharing one or more pairs of valence electrons to achieve stable electron configurations.
6. Which molecule is nonpolar despite containing polar bonds?
CO2 is linear and its two C=O bond dipoles cancel, so the molecule overall is nonpolar.
7. Which pair of atoms is most likely to form a covalent bond?
Two nonmetals like chlorine share electrons to form a covalent bond; metal–nonmetal pairs tend to form ionic bonds.
8. How many electrons are shared in a double covalent bond?
A double bond consists of two shared electron pairs, so four electrons are shared between the atoms.
9. Which statement about bond order, bond length and strength is true?
More shared electron pairs (higher bond order) pull nuclei closer, shortening the bond and increasing bond energy (strength).
10. What is a coordinate (dative) covalent bond?
In a coordinate bond one atom donates both electrons to form the shared pair, for example NH3 donating to H+ to make NH4+.
11. Which common charge does calcium form to achieve a noble gas configuration?
Calcium (group 2) loses two valence electrons to form Ca2+, achieving the electron configuration of the nearest noble gas.
12. Which statement best describes metallic bonding?
Metal atoms release valence electrons that move freely; the resulting delocalised electrons hold the metal ions together.
13. What two factors determine whether a molecule is polar?
Even if bonds are polar, molecular shape determines whether bond dipoles cancel or produce a net molecular dipole (polarity).
14. What is the correct formula for the ionic compound formed from Mg2+ and Cl-?
Two chloride ions (each -1) are needed to balance one Mg2+, giving the neutral formula MgCl2.
15. What is the molecular shape of methane (CH4) according to VSEPR theory?
CH4 has four bonding pairs around carbon that arrange themselves as far apart as possible in a tetrahedral shape.
16. What is the shape of the ammonia (NH3) molecule?
NH3 has three bonding pairs and one lone pair on nitrogen; the lone pair pushes the bonds down, giving a trigonal pyramidal shape.
17. Which type of covalent bond is strongest among single, double and triple bonds?
Triple bonds involve three shared pairs of electrons, making them shorter and stronger than double or single bonds.
18. Which of these will conduct electricity in the solid state?
Metals conduct in the solid state because delocalised electrons are free to move; ionic solids conduct only when molten or dissolved.
19. What is the bond order of the oxygen molecule O2 (written as O=O)?
O2 has a double bond between the oxygen atoms, which corresponds to a bond order of 2.
20. What is the shape of the carbon dioxide (CO2) molecule?
CO2 has two double bonds on the central carbon and no lone pairs; the bonds are opposite each other, giving a linear shape.
21. Which element is most likely to form covalent bonds in compounds?
Carbon is a nonmetal with four valence electrons, commonly forming covalent bonds by sharing electrons with other nonmetals.
22. What are lone pairs in Lewis structures?
Lone pairs are pairs of valence electrons localized on an atom that are not used to form covalent bonds.
23. Why do ionic crystals form a lattice structure?
Ionic crystals arrange ions in a regular repeating lattice so opposite charges are next to each other, lowering the system's energy.
24. How many valence electrons does a neutral sulfur atom have?
Sulfur is in group 16 of the periodic table and has six valence electrons in its outer shell.
25. Which species contains a coordinate (dative) bond?
In NH4+ one hydrogen is bonded to nitrogen by accepting a lone pair from NH3; the N→H bond is a coordinate (dative) bond.