Elements that are generally poor conductors of heat and electricity are known as what?

Introduction / Context:
One of the earliest ways to classify elements is to divide them into metals and non metals based on physical properties such as lustre, malleability, and ability to conduct heat and electricity. This simple classification is very useful in general science and chemistry. The question asks which group of elements is usually a poor conductor of heat and electricity, a key distinguishing feature from metals.

Given Data / Assumptions:

• We are comparing broad groups of elements based on physical properties.
• Options include metals, non metals, halogens, noble gases, and metalloids.
• We assume standard temperature and pressure and ordinary conditions, not special forms like plasma.
• We focus on overall trends, not rare exceptions.

Concept / Approach:
Metals are typically good conductors of heat and electricity because they have free electrons that move easily through the metallic lattice. Non metals, in contrast, generally lack such free electrons and therefore conduct heat and electricity poorly. Halogens and noble gases are actually subgroups within non metals, and metalloids have intermediate properties. The broad category that captures elements which are poor conductors is non metals.

Step-by-Step Solution:
Step 1: Recall that metals like copper, aluminium, and silver are used in electrical wiring and cookware because they conduct heat and electricity very well. Step 2: Non metals include elements such as carbon (in many forms), sulfur, phosphorus, oxygen, nitrogen, and chlorine. Step 3: Most non metals exist as brittle solids, gases, or liquids and do not have freely moving electrons in a metallic lattice. Step 4: As a result, they are generally poor conductors of heat and electricity under normal conditions. Step 5: Halogens and noble gases are specific families of non metals, not separate overarching categories for basic classification. Step 6: Therefore, the correct answer describing elements that are poor conductors is non metals.

Verification / Alternative check:
Everyday examples support this classification. Electrical cables are made of metallic conductors, while insulating materials around those cables are often plastics derived from non metallic elements such as carbon, chlorine, and hydrogen. Air, which consists mainly of the non metals nitrogen and oxygen, is a very poor conductor of electricity and heat, except under extreme conditions. In contrast, metals quickly transfer heat, which is why cooking utensils are metal but often have non metallic handles to reduce heat conduction to the hand.

Why Other Options Are Wrong:
Metals: Known for high electrical and thermal conductivity, so they are the opposite of poor conductors.
Halogens: A subgroup of non metals, but the general classification used in school textbooks is metals versus non metals; halogens alone do not represent all poor conductors.
Noble gases: These are inert non metals but exist as gases and are a small subset; the basic term for poor conductors as a group is non metals.
Metalloids: Elements like silicon and germanium have intermediate properties and can sometimes conduct under specific conditions but do not define the general group of poor conductors.

Common Pitfalls:
Students sometimes get distracted by more specific names such as halogens or noble gases and forget that these are subgroups within the broader non metal category. Another mistake is focusing on exceptions like graphite, a form of carbon that conducts electricity, and then feeling uncertain. It is important to remember that classification is based on general trends, and overall non metals are poor conductors compared to metals.

Final Answer:
Elements that are poor conductors of heat and electricity are classified as non metals.