Atomic Models in Science History

An atom consists of a central nucleus of positive charge, around which negatively charged ______ revolve

The nucleus of an atom is made up of ______ which are positively charged, and neutrons which are electrically neutral

Each element has a certain number of ______ and protons

An electron has a radius of about 10-15 meter and is more than twice as big as a ______

An electron has a mass of about 9.11 x 10-28 grams. A proton is heavier than an electron (around 1840 times heavier than ______)

A neutron has about the same mass as a ______

The positive charge on each proton is equal in magnitude to the negative charge on each ______.

An atom is electrically neutral in its stable state (number of ______ = number of protons).

The outermost shell contains not more than 8 ______.

The outermost shell determines the chemical valence and physical characteristics of an ______.

The number of electrons in an incomplete outermost unfilled shell is called ______ electrons.

Trivalent elements have three valence ______.

Materials capable of having many free electrons and carrying electric current are called ______

Materials which are only capable of having very few free electrons are called ______

Materials which are capable of having not so many free electrons are called ______

An atom or molecule that has become charged or electrically unbalanced is called an ______

A positive ion is called a ______

Electrons may leave a certain material through the process of ______