Ionic salts are characterized by strong electrostatic forces between ions, resulting in high melting points and high boiling points. The statement claiming they have low melting points is incorrect, as significant energy is required to break the rigid crystal lattice structure.
3042
Which type of chemical bonding is primarily characterized by the donation of a proton or the involvement of a coordinate covalent bond?
A coordinate covalent bond, also known as a dative bond, involves the sharing of a pair of electrons where both electrons originate from one of the two atoms. While protons are central to acid-base chemistry, the coordinate bond is specifically defined by this donor-acceptor electron pair mechanism, distinguishing it from standard covalent or ionic interactions.
3043
Which of the following compounds contains both ionic and covalent bonds within its structure?
Sodium hydroxide (NaOH) is an ionic compound composed of Na+ cations and OH- anions. The bond between the sodium ion and the hydroxide ion is ionic. Within the hydroxide polyatomic ion itself, the oxygen and hydrogen atoms are held together by a polar covalent bond. Therefore, NaOH contains both types of bonding.
3044
An element 'A' forms an oxide with the formula A2O3. What is the valency of element A?
In the formula A2O3, oxygen has a valency of 2. The total negative charge from three oxygen atoms is 3 × 2 = 6. To maintain electrical neutrality, the two atoms of element A must contribute a total positive charge of +6. Dividing this by the two atoms of A gives a valency of +3 for element A.
3045
Which of the following is a characteristic property of ionic compounds?
Ionic compounds consist of a lattice of positive and negative ions held together by strong electrostatic forces. These strong forces require significant energy to overcome, resulting in high melting and boiling points. They are typically hard, brittle, and soluble in polar solvents like water, rather than non-polar solvents like kerosene.
3046
What type of chemical bond exists between the two atoms in an oxygen molecule (O2)?
In an oxygen molecule (O2), each oxygen atom has six valence electrons. To achieve a stable octet configuration, the two atoms share two pairs of electrons, resulting in the formation of a double covalent bond between them.
3047
What are the fundamental structural units that constitute electrovalent compounds?
Electrovalent compounds are formed by the electrostatic attraction between oppositely charged ions. These ions are either individual charged atoms (like Na+ or Cl-) or polyatomic groups of atoms that carry a net charge (like SO4 2-). These charged species are the building blocks of the ionic crystal lattice.
3048
Which of the following substances is classified as a covalent compound?
A covalent compound is formed by the sharing of electron pairs between atoms, typically non-metals. Carbon tetrachloride (CCl4) consists of carbon and chlorine, both non-metals, which share electrons to form covalent bonds. In contrast, calcium chloride, magnesium fluoride, and sodium chloride are ionic compounds formed by the electrostatic attraction between metal cations and non-metal anions.
3049
What is the valency of chlorine in relation to oxygen in compounds like chlorine heptoxide (Cl2O7)?
In the compound Cl2O7, oxygen typically exhibits a valency of 2. Since there are seven oxygen atoms, the total valency contributed is 14. Dividing this by the two chlorine atoms gives a valency of 7 for each chlorine atom, demonstrating its ability to expand its valence shell.
3050
Identify the incorrect match between the element and its typical valency.
Oxygen typically has a valency of 2 because it requires two electrons to complete its valence shell. The match 'Oxygen: 1' is incorrect as it does not represent the standard combining capacity of oxygen in most stable compounds.
