Physical Science

Plasma is widely considered the fourth state of matter, following solids, liquids, and gases. It consists of ionized gas where electrons are stripped from atoms.

In physics, energy is broadly categorized into potential energy (stored energy) and kinetic energy (energy of motion). All other forms of energy are typically variations or combinations of these two.

All matter is composed of atoms, which are the basic building blocks of elements. While atoms contain protons and electrons, and can form molecules, the fundamental particle of matter is the atom.

Toasting bread involves a chemical reaction (the Maillard reaction) that changes the chemical composition of the bread, creating new substances like melanoidins. This is a chemical change because the original substance cannot be easily reversed to its raw state.

Spreading butter on bread changes the shape and location of the butter, but it does not change the chemical composition of either the butter or the bread. Therefore, it is a physical change.

Gases do not have a definite shape or a definite volume; they expand to fill the entire container they are in. Solids and liquids have definite volumes.

A solid has a definite shape and a definite volume. Liquids have a definite volume but not a definite shape, and gases have neither.

Mass is defined as the amount of matter in an object. It is a constant property regardless of the gravitational pull acting on the object.

Weight is the measure of the force of gravity acting on an object's mass. Unlike mass, weight changes depending on the gravitational field strength.

A physical change affects the form of a chemical substance, but not its chemical composition. No new substance is formed during a physical change.

Physical properties are characteristics of matter that can be observed or measured without changing the chemical identity of the substance. Odor, mass, density, volume, color, and state are all physical properties.

The release of heat (exothermic reaction) is a common indicator that a chemical change has occurred, as it suggests the formation of new bonds and a change in chemical energy.

Physical properties are defined as characteristics that can be observed or measured without altering the chemical composition of the material.

Elements are the basic kinds of matter that cannot be broken down into simpler substances by chemical means. There are over 100 known elements.

A chemical change describes the process by which a substance undergoes a reaction to become a different substance with new properties.

Buoyancy is the upward force exerted by a fluid that opposes the weight of an immersed object. It depends on the density of the object relative to the density of the fluid.

In a liquid, particles are close together but have enough energy to move past one another, which allows liquids to flow and take the shape of their container.

In a gas, particles are far apart and move rapidly and randomly. Because of the large spaces between particles, gases are easily compressed.

Freezing is the phase transition where a substance changes from a liquid to a solid. Melting is the reverse process, while addition of heat and thermal energy are concepts related to energy transfer rather than the state change itself.

Density is defined as the mass of a substance per unit volume. Therefore, the formula is Density equals Mass divided by Volume.

Condensation is the process where gas particles lose energy, slow down, and transition into a liquid state. Vaporization is the opposite process where a liquid turns into a gas.

Carbon dioxide is a chemical compound that exists as a gas at room temperature and standard atmospheric pressure. It is not a liquid, solid, or plasma under these common conditions.

According to the kinetic molecular theory, particles of matter are in constant motion, even in solids where they vibrate in place. This motion only ceases at absolute zero.

A liquid has a definite volume because its particles are close together, but it takes the shape of its container because the particles can slide past each other. Gases have no definite shape or volume, and solids have both.

Matter is defined as anything that has mass and takes up space (volume). Solids, liquids, and gases are all specific states of matter.

A chemical change occurs when substances react to form entirely new substances with different chemical properties. Physical changes only alter the appearance or state of a substance without changing its identity.

Digestion involves enzymes and acids breaking down food into different chemical components, which is a chemical change. Physical digestion, like chewing, is a physical change, but the overall process is primarily chemical.

The souring of milk is caused by bacteria producing lactic acid, which changes the chemical composition of the milk. This is a classic example of a chemical change.