How can matter be classified?

Matter is made up of a basic “ingredient” known as atom. Atoms are the smallest units of an
element that maintains the properties of that element. The substances you encounter every
day can be classified in three major classes: Elements, Compounds, and Mixtures. They are all
made up of atoms but the atoms are mixed in different ways in each one of them.

You can picture atoms as building blocks and you can organize them in this way. If you put
one or more atoms of the same kind together the result will be an element, but, if you put two
or more atoms of a different kind what you will get is a compound. When you mix elements
and compounds what you get is a mixture.

What are pure substances?

Elements and compounds are pure substances. A pure substance is a substance that has
definite physical and chemical properties. This happens because pure substances are the ones
made of one type of particle. Even so compounds are pure substances because even though its
not the same kind of atom it’s the same kind of molecule. A molecule is a combination of two
or more kinds of atoms that are chemically combined.

Pure substances cannot be formed or broken down by physical changes. When a pure
substance undergoes a chemical change its no longer that same substance. Individual atoms
cannot be broken down by any normal physical or chemical change.

How can elements be classified?

There are over 100 elements but based on its physical and chemical properties we can
know to which category an element belongs to, by knowing this we can infer some of its
characteristics. They can be classified as metal, non metal, and metalloids. Metals tend to be
shiny, be good heat and electricity conductors and be molded into sheets or wires, non metals
are not shiny and they do not conduct heat or electricity well. Metalloids have characteristics
from both metal and non metal elements.

How can compounds be classified?

Compounds are classified by their pH into three different kinds: Neutrals, Bases and Acids.
Acids have a pH below 7, bases have a pH greater than 7 and neutrals have a pH of 7. They
can also be classified into organic and inorganic. Organic compounds are the ones who
contain carbon or hydrogen whereas inorganic ones don’t. compounds are also classified by
their role in the body. There are categories: lipids, carbohydrates, nucleic acids and proteins
Carbohydrates are used as a source of energy, lipids store excess energy in the body, protein
regulate chemical activities in the body and nucleic acids contain genetic information.

What are mixtures?

A mixture is a combination of two or more substances that are combined physically but
not chemically. Unlike elements and compounds a mixture is not a pure substance. Mixture
contain more than one substance but those substances have the same chemical make-up
they had before being mixed together. Mixtures can be separated by physical changes easily

because they are not combined chemically.

How can mixtures be classified?

There are two ways to classify mixtures, one is by the way they look. If we classify them this
way there are 2 kinds of mixtures the heterogeneous and the homogeneous. Homogeneous
mixtures are the ones in which substances are evenly spread and Heterogeneous one are the
ones in which you can spot its different substances.

But there is another way you can look at mixtures you can see them as suspensions, colloids,
and solutions. In a suspension particles are spread in a liquid or a gas but are too large to stay
mixed without being stirred. In solutions one substance is dissolved in another. And in colloids
it’s like both of them, the particles do settle but they settle really slow.

-Claudio

States of Matter

States of Matter

All mater is made of atoms or groups of atoms that are in constant motion. This idea is the
basis for the kinetic theory of matter

• Solid: is a substances that has a definite volume and shape
• Liquid: is a substance that has a definite volume but not a definite shape
• Gas: is a substance that does not have a definite volume or shape

The solids have a volume and a definite shape because the atoms are in a determine
position and place that form a object that can feel and touch

The liquids have a definite volume but can change shape because his atoms are in all parts
and in a very small space that separate. The liquids can absorb the shape of the recipient

The gas can change in volume and shape because his atoms are in all parts and have a big
space that separate

-Francesco

Changes of State

What happens when matter changes state?

         A change of state is the change of substance from one physical form of matter to another. When a substance experiences a physical change, it does not change its identity, just its appearance. In order to change a substance from one state to another, energy must be added or moved. While a substance gains or loses energy, its temperature or state changes. The temperature and state do not change at the same time because the temperature does not change till after the change of state.

         Matter is made of tiny particles that are in constant motion. The motion of the particles changes in the middle of a change of state. Particles can break away from each other and gain more freedom to move like when a solid changes to a liquid, or vice versa. The particles can also attract each other more strongly, and have less freedom to move. For example, when gas changes to a liquid, or a liquid changes to a solid. During a change of state, a substance must gain energy from the environment or loss energy to the environment while maintaining the total amount of energy preserved. Like a water cycle, each change of state represents a transfer of energy either into or out from the surrounding environment. But energy is never created or destroyed.

How do solids and liquids change states?

         Particles in a liquid can slide past each other, yet particles in a solid can only move enough to vibrate. By removing energy from a liquid can cause it to change to a solid. Adding energy to a solid can cause it to change to a liquid. It is called freezing when the change of state changes a liquid to a solid. The liquid has to be at freezing point in order for the substance can change into a solid. The change of state in which changes a solid to a liquid is called melting and the temperature at which the substance changes from a solid to a liquid is called the melting point.

How do liquids and gases change state?

         Particles in a gas have a great deal of energy. When removing enough energy from a gas causes a gas to change a liquid or a solid and adding enough energy to a liquid or a solid causes it to change into a gas. This process is called vaporization. Vaporization can happen in three different ways: evaporation, boiling and condensation. Evaporation occurs when a liquid gets warmed slowly and the higher the temperature the faster the liquid turns to gas. A rapid change from a liquid to a gas is called boiling and it has to be at a specific temperature in order for this to occur which is called the boiling point. The greater the air pressure, the higher the boiling point of a liquid. Condensation is the reverse of evaporation. This is the change of state from a gas to a liquid.

How do solids and gases change state?

Some solids and gases can change state without ever becoming a liquid, which can only occur in sublimation and deposition. The change from a solid to a gas is called sublimation. As the particles of solid dry ice gain energy their motion overcomes the attraction making the particles escape into the air as gas. Deposition is the change of state from a gas to a solid. This can only happen when ice crystals form in clouds.

What happened to matter when a change of state occurs?

         Matter changes from one state to another; it remains the same kind of matter. Its physical state changes, but its chemical identity does not. It makes it a change of state because the energy, movement, and the distance between the particles changes. The mass of a substance does not change when its state changes, making each state contain the same amount of matter.

Yesenia Gomez

            

Welcome!

This is a fun place to learn about science and all of its facts. Science may teach us many things that all though we find irrelevant, actually explain how the world works.

-Andrés