Important Definitions and Laws: Science and Technology Part I and Periodic Classification of Elements

Flashcards of vocabulary terms and definitions from the provided lecture notes on gravitation, Kepler's laws, Newton's law of gravitation, acceleration due to gravity, free fall, escape velocity and periodic classification of elements.

Centripetal Force

A force which acts on any object moving along a circle and is directed towards the centre of the circle.

Kepler's First Law

The orbit of a planet is an ellipse with the sun at one of the focci.

Kepler's Second Law

The line joining the planet and the sun sweeps equal areas in equal intervals of time.

Kepler's Third Law

The square of the period of revolution (T) of a planet around the sun is directly proportional to the cube of the mean distance (r) of a planet from the sun.

Newton's Universal Law of Gravitation

Every object in the Universe attracts every other object with a definite force which is directly proportional to the product of their masses and is inversely proportional to the square of the distance between them.

Acceleration Due to Gravity (g)

Acceleration caused in a body due to a gravitational force.

Free Fall

Any motion of a body where gravity is the only force acting upon it.

Escape Velocity (Vesc)

The minimum velocity needed for an object to escape from the gravitational influence of a massive body.

Mass

The matter present in a body.

Weight

The gravitational Force acting on body.

Dobereiner's Triad

A group of three elements having similar chemical properties.

Dobereiner's Law of Triad

When three elements having similar chemical properties arranged in a triad in increasing order of their atomic masses then the atomic mass of the middle element was approximately equal to the mean of the atomic masses of the other two elements.

Newlands' Law of Octave

When the elements were arranged in increasing order of their atomic masses then every eighth element had properties similar to those of the first.

Inert Gases

All shells are completely filled.

Normal elements or representative elements

Only last orbit is incompletely filled.

Transition Elements

Last two shells are Incompletely filled.

Inner Transition Elements

Last three shells are incompletely filled.

Period

A horizontal row of the periodic table equal to the number of shells present in an atom of an element.

Alkali and Alkaline Earth Metals

Groups 1 and 2.

Halogens

Group 17 elements.

Metalloids

Elements lying along the border of the zig zag line separating metals and nonmetals.

Valency

The number of valence electrons of an element.

Atomic Radius

The distance between the nucleus of the atom and it's outermost shell.

Electro Positivity

The tendency of a metal to lose the valence electrons to for cation.

Electronegativity

The tendency of an element to accept electron to form anion.