Physical Sciences Definitions PDF

**[Physical Sciences:]** **Chemistry Definitions:** **Atomic Structure** Atomic number- Number of protons in the nucleus of an atom and number of electrons in a neutral atom. Mass number- The number of protons and neutrons (nucleons) in the nucleus of an atom of an element. Isotopes- Atoms of t...

**[Physical Sciences:]** **Chemistry Definitions:** **Atomic Structure** Atomic number- Number of protons in the nucleus of an atom and number of electrons in a neutral atom. Mass number- The number of protons and neutrons (nucleons) in the nucleus of an atom of an element. Isotopes- Atoms of the same element, having the same atomic number (number of protons) but having different mass numbers (different number of nucleons). Relative atomic mass- A number which indicates how many times the average mass of an atom of a certain element is heavier than 1/12^th^ of a carbon-12 atom. Orbitals- Those permitted spaces in the different energy levels where the probability of finding electrons is the greatest. Valence electrons -The electrons found in the outermost energy level of an atom. Valency- A number which indicates how many bonds that atoms of an element can form. **Quantitative Chemistry** Mole- The SI unit for amount of substance. Molar mass- The mass in grams of one mole of that substance. Molar volume- 1 mole of any type of gas occupies a volume of 22,4dm3 at STP. Solution- A homogenous mixture of a solute and solvent Solute- A substance dissolved in a solution. Solvent- Substance in which another substance is dissolved, forming a solution. Concentration- Number of moles of solute per unit volume of solution. Yield- A measure of the extent of a reaction, generally measured by comparing the amount of product against the amount of product that is possible. **Chemical Bonding** Electrostatic force- A force between positive and negative charges. Intramolecular bond- A bond which occurs between atoms within a molecule Covalent bond- A sharing of at least one pair of electrons by two atoms. Electronegativity- A measure of the tendency of an atom to attract a bonding pair of electrons. Ionization energy- The energy required to remove an electron from an atom in the gaseous phase. Metallic bond- The attraction between positive kernels and a sea of delocalized electrons. Intermolecular force- The forces of attraction between molecules or atoms of a noble gas. Allotropes - substances made up of the same element having different physical structures. **Physics Definitions:**  **Vectors and Scalars (Kinematics)** Scalar- A physical quantity that has magnitude only. Mass (scalar)- A property of a body that is a measure of the amount of matter that a body or object contains. Vector- A physical quantity that has both magnitude and direction. Weight/ Gravitational force (vector)- The gravitational force the Earth exerts on any object on or near its surface. Resultant- The single vector which will have the same effect as all the original vectors acting together. **Displacement, Velocity and Acceleration (Kinematics)** Position (scalar)- A scalar quantity that is the location of an object relative to a reference point. Change in position (vector)- The difference between the final and initial positions. Distance (scalar)- The length of the path travelled. Displacement (vector)- A change in position Speed (scalar)- The rate of change of distance. Velocity (vector)- The rate of change of position. Instantaneous speed- The speed of an object at a specific moment in time. Instantaneous velocity- The velocity of an object at a specific moment in time. Acceleration (vector)- The rate of change in velocity. Free fall - Motion, upwards or downwards in Earth's gravitational field, when no other forces act on the object. Equilibrant- The single vector that will bring all the original vectors into equilibrium. Equilibrium- The forces acting on an object is in equilibrium when the resultant of all the forces is zero Normal force- The perpendicular force exerted by a surface on an object in contact with it. Frictional force- The force that opposes the motion of an object. Newton's first law of motion- An object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force. Inertia- The property of an object that causes it to resist a change in its state of rest or uniform motion. Newton's third law of motion- When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A. Newton's second law of motion- When a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass. **Momentum, Impulse, Work, Energy and Power** Momentum -- Linear momentum is the product of the mass and the velocity of an object. Impulse -- Impulse is the product of the net force and the contact time. Alternative Newton's second law- The net force acting on an object is equal to the rate of change of momentum. Principle/law of conservation of momentum- The total linear momentum of an isolated system remains constant. Elastic collision - A collision in which both momentum and kinetic energy are conserved. Inelastic collision -- A collision in which only momentum is conserved. Gravitational potential energy -- The energy an object possesses due to its position relative to a reference point. Kinetic energy -- The energy an object has as a result of the object's motion. Mechanical energy -- The sum of the gravitational potential energy and the kinetic energy at a point. Principle of mechanical energy -- In the absence of air resistance or any external forces, the mechanical energy of an object is constant. Law of conservation of energy -- The total energy in a system cannot be created nor destroyed, only transformed from one form to another. Work -- The product of the displacement and the component of the force parallel to the displacement. Work-Energy theorem -- The work done by a net force on an object is equal to the change in kinetic energy of the object. Power -- The rate at which work is done or the rate at which energy is transferred. One watt -- The power when one joule of work is done in one second. Efficiency -- The ratio of output power to input power. Isolated system -- A system that is free from the influence of a net external force that alters the momentum of the system. Non-conservative force -- The work done by the force depends on the path taken by the object. **Electrostatics, Electric Fields, and Gravitational Fields** Law of Conservation of Charge -- The algebraic sum of the charges in an isolated system will remain constant. Coulomb's law -- Two-point charges exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square distance between the charges. Electric Field at a Point -- The force per unit positive charge. Describe an electric field as a region of space in which an electric charge experiences a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point. Charge -- A property of a proton and an electron. Newton's Universal Law of Gravitation - Every particle with mass in the universe, attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. Gravitational Field -- The force acting per unit mass. Describe a gravitational field as a region in space where a mass will experience a force.