Science Scope and Sequence, The Atom

Science Standard III, Chemistry

Lesson 310, The Atom

Defining atom and element

Understanding the impact of Democritus on the discovery of the atom

Recognizing the main points of Dalton’s atomic theory: all elements are composed of atoms that cannot be divided or destroyed; atoms of the same element are exactly alike; atoms of different elements are different; compounds are formed when the atoms of two or more elements are joined

Describing Thomson’s atomic model: the “plum pudding” model: In it, negatively charged particles are scattered throughout a positively charged material

Describing Rutherford’s atomic model: positively charged particles form the small, dense center of the atom. This positively charged center is called the nucleus. Negatively charged electrons are scattered outside the atom’s nucleus.

Defining atomic mass

Knowing that different elements will have different atomic masses


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