Iodide - (I-)

What is Iodide?

Iodide is an anion with a valency of -1. Compounds of iodine with oxidation state as -1 are called iodides. The chemical formula for iodide is I.

Iodine as an element is a halogen. It tends to accept an electron and exists as a negatively charged ion. Therefore, the anion name iodide is used interchangeable with iodine.

IUPAC name – Iodide

I Iodide
Density 3.13 g/cm3, solid
Molecular Weight/ Molar Mass 126.904 g/mol
Boiling Point 184.3 °C
Melting point 113.7 °C
Chemical Formula I

Iodide Structure – I

Iodide Structure

Iodide Structure

Physical Properties of Iodide – I

Odour Irritating odour
Appearance purple-pink gas, solid iodine is dark grey or purple color.
Electronegativity 2.5
Specific heat 0.214
Solubility 128 g/100 ml (6 °C)

Chemical Properties of Iodide – I

  1. Sodium salt of iodide reacts with lead nitrate forms a yellow precipitate of lead iodide and sodium nitrate.Pb(NO3)2(aq) + 2 NaI(aq) → 2 NaNO3(aq) + PbI2(s)(yellow precipitate)
  2. Iodide salt of potassium reacts with chlorine forming potassium chloride and iodine. Chlorine replaces iodine because chlorine is more reactive than iodine.2KI + Cl2 → 2KCl + I2

Uses of Iodide – I

  • Iodide has a disinfectant property and is not readily affected as chlorine by water pH or organic content but iodide disinfectant activity is markedly reduced by cold water temperature.
  • Potassium iodide is added as a nutrient to prevent goiter a thyroid problem caused by lack of iodine and prevent a form of mental retardation associated with iodine deficiency.
  • Iodine preparations such as povidone-iodine are used to disinfect skin before surgery. Allergic reactions to iodine are common and should be carefully evaluated because the resultant stain maymask redness and swelling.

Health Hazard

The primary effects of long term oral exposure to elevated amounts of inorganic iodide are paradoxically, hyperthyroidism and hypothyroidism. Excess intake of iodide can inhibit thyroid hormone synthesis and release which may result in hypothyroidism and goitre.

Frequently Asked Questions

What is iodide used for?

Potassium iodide (KI) is a chemical compound that can be used to shield the thyroid gland from potential radioactive iodine damage (radio iodine). Some radio logical emergencies can emit large amounts of radio iodine into the air.

Where is iodide found?

Iodine is naturally found in the ocean, and it is preserved in its tissues by certain sea fish and water plants. Iodine can be present in the air, water and soil, naturally. The seas are the primary sources of natural iodine.

What is the Valency of iodide?

Iodine valence is -1 because in its last shell it has 7 electrons and receives one electron to make it stable.

Is iodized and iodide the same thing?

Therefore iodine and iodide are only different expressions of the same product. Iodides only reflect a healthy ingestion form of iodine. Iodides also have the drawback of requiring extra body energy to sever the iodide bond to use the iodine.

What is iodide good for?

Iodine lowers thyroid hormone and can destroy microorganisms such as amoebas, fungi, bacteria, and others. A particular form of iodine called potassium iodide is often used to treat the effects of a nuclear accident, but does not prevent them.

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