Question

Identify each of the following elements as a metal, non metal, or metalloid: (a) gallium, (b) molybdenum, (c) tellurium, ( \(\mathbf{d}\) ) arsenic, (e) xenon, (f) ruthenium.

Short answer

(a) Gallium is a metal, (b) Molybdenum is a metal, (c) Tellurium is a metalloid, (d) Arsenic is a metalloid, (e) Xenon is a non-metal, and (f) Ruthenium is a metal.

Step-by-step solution

(a) Gallium

Gallium, with symbol Ga and atomic number 31, is a metal. It is found in group 13 (also known as group IIIA) in the periodic table, and all elements in this group are metals. Therefore, gallium is a metal.

(b) Molybdenum

Molybdenum, with symbol Mo and atomic number 42, is a metal. It is found in group 6 (also known as group VIB) in the periodic table, which mainly consists of transition metals. Therefore, molybdenum is a metal.

(c) Tellurium

Tellurium, with symbol Te and atomic number 52, is a metalloid. It is found in group 16 (also known as group VIA) in the periodic table, adjacent to the metalloid line dividing metals and non-metals. The elements in this group show properties which are intermediate between metals and non-metals, classifying tellurium as a metalloid.

(d) Arsenic

Arsenic, with symbol As and atomic number 33, is a metalloid. It is found in group 15 (also known as group VA) in the periodic table, adjacent to the metalloid line dividing metals and non-metals. The elements in this group show properties which are intermediate between metals and non-metals, classifying arsenic as a metalloid.

(e) Xenon

Xenon, with symbol Xe and atomic number 54, is a non-metal. It is found in group 18 (also known as group VIIIA) in the periodic table, which are noble gases. The noble gases are non-metals, and therefore, xenon is a non-metal.

(f) Ruthenium

Ruthenium, with symbol Ru and atomic number 44, is a metal. It is found in group 8 (also known as group VIIIB) in the periodic table, which mainly consists of transition metals. Therefore, ruthenium is a metal.

Key concepts

Metals

The metals on the periodic table are the most abundant elements, recognized for their unique properties. Typically, metals are solid at room temperature (except for mercury), show high electrical and thermal conductivity, and possess a shiny, lustrous appearance.
Common characteristics of metals include:

• Malleability: the ability to be hammered or rolled into sheets.
• Ductility: enables them to be stretched into wires.
• Conductivity: excellent carriers of heat and electricity.
• High Density: generally heavier than non-metals.

Metals occupy the left portion of the periodic table, ranging from alkali metals in group 1 to transition metals located in the central block. Transition metals, like molybdenum and ruthenium, are known for forming complex ions and compounds. Gallium is another metal belonging to group 13, highlighting the diversity among these elements.

Metalloids

Metalloids represent a unique class of elements that display properties of both metals and non-metals. These elements form a zigzag line on the periodic table, acting as a bridge between the two categories. Because of their hybrid nature, metalloids such as arsenic and tellurium are highly valuable in industry.
Key features of metalloids include:

• Semi-conductive: moderate electrical conductivity, which increases with temperature.
• Luster: they often appear shiny.
• Complex Chemical Behavior: can form alloys with metals and halides with non-metals.

Due to their dual characteristics, metalloids are widely used in electronics as semiconductors. Arsenic and tellurium are crucial for making semiconductors for various electronic devices.

Non-metals

Non-metals are elements mostly appearing on the right side of the periodic table. They differ markedly from metals and are essential for life as we know it. With properties vastly distinct from metals, non-metals like xenon play unique roles.
Some typical properties of non-metals are:

• Non-conductive: poor conductors of heat and electricity.
• Brittle: solid non-metals tend to break or shatter easily.
• Varied State Presence: exist in solid, liquid, and gas forms at room temperature.

Noble gases, a subgroup of non-metals including xenon, are inert and hardly react with other substances. They are located in group 18 and are used in lighting and insulation applications due to their non-reactivity.

Element Classification

Element classification provides a systematic way to categorize elements based on their physical and chemical characteristics. Understanding this classification helps predict element behavior and their interactions.
The main categories are:

• Metals: often dense, conductive, and malleable.
• Metalloids: display mixed features of both metals and non-metals.
• Non-metals: generally insulative, diverse in state, and essential for biological life.

The periodic table serves as a useful tool for classifying elements, using rows and columns to group similar elements together, revealing trends in element properties. This system allows chemists to predict how elements might react under various conditions or with other elements. Proper classification is key for advancements in technology, chemistry, and materials science.