Properties of elements and compounds

Welcome to MindMentor!

Properties of elements icon

Middle School Chemistry

Properties of Elements and Compounds

Properties of elements and compounds diagram

Everything around you is made of substances. The spoon you use to eat, the water you drink, and even the air you breathe. Some of these substances may be simple, while others may be complex. Yet, each of these has properties that determine how they look, behave, and react. In chemistry, the aim is to remove the guesswork. We take time to study these properties to determine the composition of each of these substances and the possible changes that can take place.

Chemistry is the bridge between "this looks shiny" and "this is a metal with high electrical conductivity". There is a significant difference between the two statements. This degree of knowledge is what allows scientists to make material selections, predict and design reactions and products.

What Is an Element?

An element is a substance that has only one type of atom. Elements can be classified using their properties. For example, the Periodic Table classifies all of the known elements based on their properties.

Properties make it easier for us to analyze and distinguish each metal. These properties allow us to distinguish metals from non-metals, and metals from metalloids.

Metals

  • Shiny surfaces
  • Excellent conductors of heat and electricity
  • Malleable (can be reshaped)

Non-metals

  • Usually dull
  • Poor conductors of heat and electricity
  • Gases, liquids, or brittle solids

Metalloids

  • Mixture of both metals and non-metals
  • Semiconductors

Physical Properties of Metals

Physical properties are the properties that can be observed for a material without changing the material itself. This also involves the safe use of materials.

Some of the common physical properties are:

  • Color and appearance: Shiny, dull, transparent, or opaque
  • State of matter: Solid, liquid, or gas
  • Density: Different weights and volumes
  • Melting and boiling points: Temperatures at which state changes occur
  • Electrical conductivity: Ability to conduct electricity
  • Thermal conductivity: Ability to conduct heat

Some metals have high conductivity, making them very useful for wires. Other materials have low density and can be useful for structures that require lightweight materials.

Chemical Properties of Metals

Chemical properties of metals show how a material will behave in relation to other materials and change to form other new materials. It's possible to evaluate a substance by determining its components and assessing its:

  • Reactivity
  • Flammability
  • Probabilities to interact with acids, rust, and water
  • Rust and corrosion properties

Compounds

A compound is a substance formed when two or more elements chemically combine in fixed proportions. For example, hydrogen and oxygen combine to form water, which has new properties different from the individual gaseous properties.

A compound can now be defined as:

  • A determined composition, unique from elements
  • New properties from presented elements
  • A chemical composition indicative of the type and quantity of elements as demonstrated in an equation

Physical Properties of Compounds

The physical properties of a compound may depend on:

  • Melting and boiling points
  • Solubility in water
  • Rigidity/hardness
  • Electrical conductivity (in solids or when dissolved)

The compound may additionally exhibit its unique characteristics as a result of its elemental breakdown and determined chemical properties upon interacting with acids, bases, or oxygen.

Chemical Properties of Compounds

  • Reactions of compounds with acids, bases, or oxygen
  • Thermal stability
  • Simpler substance decomposition

Ionic compounds are usually difficult to break apart and have high melting points. Covalent compounds can break apart and usually have lower melting points and can exist as gases, liquids, or solids.

Structure and Bonding: Why Properties Differ

The arrangement of the atoms determines the physical and chemical properties of the compound or the element. This is why an element or compound can exist as a solid, liquid, or gas.

Key ideas include:

  • Bonding type determines the melting point and how conductive a material is
  • Arrangement of particles determines the strength and how hard a material is
  • Attraction and repulsion of particles determines boiling point and how soluble a material is

Understanding why certain structures exist helps us understand why salt can dissolve in water, and sand can't. Or why some materials can only conduct electricity when dissolved in water.

Comparing Elements and Compounds

Elements

  • Consists of only one kind of atom
  • Cannot be separated into simpler substances by chemical means
  • Possess a distinct set of physical and chemical properties

Compounds

  • Consists of two or more elements in chemical combination
  • Are separable into simpler substances by chemical means
  • Possess new properties that are different from those of their constituent elements

Why Properties Matter in Real Life

The importance of knowing the properties of materials helps us in choosing the right materials in everyday life and in technology.

Properties help in the following:

  • Selection of the material – strong metals for constructions, light plastics for packaging
  • Safety – careful handling of reactive or toxic materials
  • Design of the product – selection of materials that are heat, water, or corrosion resistant

In electronics, depending on the stability and conductivity, certain materials are used. In construction, depending on the strength and weather resistance, certain materials are used.