Question

Provide the formula for each of the following monoatomic cations: (a) lithium ion (b) silver ion (c) iron(III) ion (d) \(\operatorname{tin}(\mathrm{IV})\) ion

Short answer

(a) Li⁺, (b) Ag⁺, (c) Fe³⁺, (d) Sn⁴⁺.

Step-by-step solution

Understanding Monoatomic Cations

A monoatomic cation is an ion consisting of a single atom with a positive charge. The charge is usually determined by the element's position on the periodic table or the information provided in the name.

Determining the Lithium Ion Formula

Lithium is an alkali metal located in Group 1 of the periodic table and typically forms a cation with a charge of +1 when it loses its one valence electron. Therefore, the formula for the lithium ion is Li⁺.

Determining the Silver Ion Formula

Silver is a transition metal and commonly forms a cation with a +1 charge. Thus, the formula for the silver ion is Ag⁺.

Determining the Iron(III) Ion Formula

The term 'iron(III)' indicates that the iron ion carries a +3 charge. This is because the Roman numeral III denotes the oxidation state of the iron. Therefore, the formula for the iron(III) ion is Fe³⁺.

Determining the Tin(IV) Ion Formula

The term 'tin(IV)' specifies that tin has a +4 charge. The Roman numeral IV indicates the oxidation state. Thus, the formula for the tin(IV) ion is Sn⁴⁺.

Key concepts

Lithium Ion

Imagine a small, light element, like lithium, that has just one electron orbiting in its outermost shell. Lithium belongs to the alkali metal group, found in the very first column of the periodic table. This simplifies our understanding of lithium atoms, as they typically lose their one valence electron to achieve a stable noble gas configuration. When lithium loses this electron, it forms a positively charged ion, denoted as Li⁺. This single positive charge comes from the loss of one negatively charged electron, giving the ion a stable state.

• Group: Alkali Metals
• Valence Electrons: 1
• Resulting Ion: Li⁺

Lithium ions are prevalent in a variety of applications, including batteries and medications for mood disorders like bipolar disorder. These applications make use of the lithium ion's properties, especially its tendency to lose an electron and form a cation easily.

Transition Metals

Transition metals, unlike lithium, are found in the central block of the periodic table, known as the d-block. They have unique electron configurations that allow them to form cations with various charges. Silver (Ag), for example, is a transition metal that commonly forms a monoatomic cation with a +1 charge, represented as Ag⁺.

• Location: D-block of the periodic table
• Common Oxidation State: +1 for silver
• Unique Characteristic: Multiple oxidation states

Transition metals can form several cationic states due to their d-orbitals, which can house multiple electrons. This characteristic explains why different transition metals can have varying charges and oxidation states.

Oxidation States

An oxidation state is a fancy term for the charge of an ion after losing or gaining electrons. The concept is critical in predicting the reactivity and formula of ions. For instance, the iron(III) ion has an oxidation state of +3, indicated by the Roman numeral III. This means iron has lost three electrons, forming the ion Fe³⁺. Similarly, for tin(IV), the oxidation state is +4, resulting in the ion Sn⁴⁺ after losing four electrons.
Understanding oxidation states involves:

• Identifying the charge: Shown by roman numerals in the name
• Relating charge to reactivity: Higher charges may affect how the ion interacts with others
• Predicting compounds: Helps in forming correct chemical formulas

Oxidation states aid in determining the electron count difference from the neutral atom, which guides chemical bonding and compound formation. This knowledge is essential when dealing with transition metals, as they frequently exhibit multiple oxidation states depending on the chemical environment.