Elements and compounds

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Periodic table and compounds

Middle School Chemistry

Properties of Elements and Compounds

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. The distinct properties of metals and metalloids are as follows:

Metals

  • Metals have shiny surfaces.
  • Metals are excellent conductors of both heat and electricity.
  • Metals are malleable. This means they can easily be reshaped to form other metallic structures.

Non-metals

  • Non-metals are usually dull.
  • Non-metals can be poor conductors of heat and electricity.
  • Non-metals can be found as gases, liquids, or brittle solids.

Metalloids

  • Metalloids are a mixture of both metals and non-metals.

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 the following:

  • Materials have different colors and appearances. They can have shiny appearances, or they can have dull appearances. They can be transparent or not.
  • Materials can also be found in different states of matter. They can be solid, liquid, or gas.
  • Materials also have different densities. This means that different materials can have different weights and different volumes.
  • Materials also have different melting points and boiling points. These are the different temperatures at which they change from solid to liquid form or from liquid to gas.
  • Materials differ in conductivity. This means that different materials have different abilities to conduct electricity.
  • Materials can also be different in thermal conductivity. This means that different materials have different abilities to conduct heat.

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

Chemical properties of metals

Chemical properties of metals are the properties that 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 components for their unique reactivity, flammability, and their probabilities to interact with acids, rust, and water, as well as their newfound rust and corrosion properties, all of which are determined by its elemental breakdown and geographical combinations as presented periodically.

Compounds

A compound, as a result of a determined, geographical interaction, creates a unique result dominated by different elemental characteristics and influences. They can contain as diverse a composition as hydrogen and oxygen, which in the compound of water would give a new property 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.

A compound exhibits its physical and chemical properties as a result of and dependent on its unique elemental breakdown, with its sub-division as a result of elemental breakdown.

The physical properties of a compound may depend on its determination:

  • Melting and Boiling Points
  • Solubility in water
  • Rigid/hard
  • Electric Conductivity (in solids or when dissolved)

The compound may additionally exhibit its unique characteristics as a result of elemental breakdown, and its determined chemical properties upon interacting, or when combined with acids, bases, or oxygen. The simplicity, or the breakdown of a substance, may determine its elemental conductivity and result in different properties.

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.

The key ideas include:

  • Bonding type determines the melting point and how conductive a material is
  • Arrangement of the particles determines the strength and how hard a material is
  • Attraction and repulsion of the 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 and compounds can be compared based on their properties and what they are made of:

Elements Compounds
Consists of only one kind of atom Consists of two or more elements in chemical combination
Cannot be separated into simpler substances by chemical means Are separable into simpler substances by chemical means
Possess a distinct set of physical and chemical properties 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 in everyday life and in industry:

  • 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, for example, depending on the stability and conductivity, certain materials are used. While in construction, depending on the strength and weather resistance, certain materials are used. Due to the ability to link properties to the structure and composition, chemistry is a practical means of tackling problems in everyday life.

MYP Journey

The MYP journey encompasses several fields such as reactions, materials, and environmental chemistry. Building a strong foundation in studying the properties of elements and compounds helps in building a strong foundation in studying these areas.