Introduction to Physical Science

The chemical formula H2O indicates two hydrogen atoms and one oxygen atom.

A compound is a substance formed when two or more chemical elements are chemically bonded together in a fixed ratio.

The nucleus contains almost all of the mass of an atom (protons and neutrons) in a very small volume, resulting in extremely high density compared to the electron cloud.

In the periodic table, the vertical columns are called groups, while the horizontal rows are called periods.

Friction is categorized into several types, including static, sliding, and rolling friction.

Momentum is calculated as mass times velocity (p = m * v). Here, 2 kg * 5 m/s = 10 kg*m/s.

Momentum is defined as the product of an object's mass and its velocity (p = mv).

According to Newton's Third Law, for every action, there is an equal and opposite reaction. The water moving forward exerts a force on the hose in the opposite direction.

Earth's gravitational acceleration (9.8 m/s²) is about 6 times stronger than the Moon's (1.6 m/s²). While mass remains constant, weight depends on gravity, so the object would weigh more on Earth.

The law of inertia (Newton's First Law) states that an object will maintain its state of motion (at rest or constant velocity) unless acted upon by an external force.

Friction is a force that opposes the relative motion of two surfaces in contact.

A vector is a mathematical or physical quantity that possesses both magnitude (size) and direction. Scalars only have magnitude, while vectors require both to be fully defined.

Equilibrium occurs when the vector sum of all forces acting on an object is zero. This means the forces are balanced, resulting in no acceleration.

According to Newton's First Law, an object with a net force of zero will maintain its state of motion. If it is already moving, it will continue at a constant velocity (speed and direction).

Speed is defined as the rate of change of position, calculated as the total distance traveled divided by the time taken to travel that distance.

In a single replacement reaction, one element replaces another element in a compound. Here, Zinc replaces Copper in the Copper(II) chloride compound.

In a chemical equation, substances to the right of the arrow are the products, which are the substances formed by the reaction. Substances to the left are the reactants.

Ionic bonds typically form between metals (which lose electrons) and non-metals (which gain electrons) due to the electrostatic attraction between oppositely charged ions.

An ionic bond involves the transfer of electrons from one atom to another to achieve a stable octet. If one atom gives electrons and another receives them, it is an ionic interaction.

Covalent bonding is characterized by the sharing of electron pairs between atoms. This occurs because the atoms involved have similar electronegativities and both need electrons to complete their outer shells.

Reactants are the starting materials in a chemical reaction, written on the left side of the arrow. CH4 and O2 are the substances reacting together.

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons, resulting in a different atomic mass.

Valence electrons are defined as the electrons in the outermost shell of an atom. These electrons are responsible for chemical bonding, and their configuration determines how an atom follows the octet rule.

Condensation is the phase change from gas to liquid. This occurs when gas particles lose kinetic energy and cluster together.

A solid is a state of matter characterized by particles packed closely together in a fixed structure, giving it both a definite shape and a definite volume.

An atom is electrically neutral when the positive charge of the protons in the nucleus is exactly balanced by the negative charge of the electrons in the electron cloud.

Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.

Atoms are the fundamental building blocks of all matter. Molecules are formed by groups of atoms bonded together.

Matter is scientifically defined as anything that has mass and takes up space (volume).