Atomic Structure

What do you know about atoms? Sticky note activity

Sizing up the atom activity Take your strip of paper and cut it into equal halves. 2. Cut one of the remaining pieces of paper into equal halves. 3. Continue to cut the strip into equal halves as many times as you can. 4. Make all cuts parallel to the first one. When the width gets longer than the length, you may cut off the excess, but that does not count as a cut. How far did you get? Here are some comparisons to think about! Cut 1 14.0 cm 5.5" Child's hand, pockets Cut 2 7.0 cm 2.75" Fingers, ears, toes Cut 3 3.5 cm 1.38" Watch, mushroom, eye Cut 4 1.75 cm .69" Keyboard keys, rings, insects Cut 6 .44 cm .17" Poppy seeds Cut 8 1 mm .04" Thread. Congratulations if your still in! Cut 10 .25 mm .01" Still cutting? Most have quit by now Cut 12 .06 mm .002" Microscopic range, human hair Cut 14 .015 mm .006" Width of paper, microchip components Cut 18 1 micron .0004" Water purification openings, bacteria Cut 19 .5 micron .000018" Visible light waves Cut 24 .015 micron .0000006" Electron microscope range, membranes Cut 31 .0001 micron .0000000045" The size of an Atom! http://www.miamisci.org/af/sln/phantom/papercutting.html

Notes As we discuss the early models of the atom, draw them on the provided worksheet Write everything in RED on a piece of paper

Which is the correct model of an atom?

Defining the Atom The Greek philosopher Democritus (460 B.C. – 370 B.C.) was among the first to suggest the existence of atoms (from the Greek word “atomos”) He believed that atoms were indivisible and indestructible His ideas did agree with later scientific theory, but did not explain chemical behavior, and was not based on the scientific method – but just philosophy To Democritus, atoms were small, hard particles that were all made of the same material but were different shapes and sizes. Atoms were infinite in number, always moving and capable of joining together.

Dalton’s Atomic Theory (experiment based!) All elements are composed of tiny indivisible particles called atoms Atoms of the same element are identical. Atoms of any one element are different from those of any other element. Atoms of different elements combine in simple whole-number ratios to form chemical compounds In chemical reactions, atoms are combined, separated, or rearranged – but never changed into atoms of another element. John Dalton (1766 – 1844) Pictured atom as sphere with no internal structure

Sizing up the Atom Elements are able to be subdivided into smaller and smaller particles – these are the atoms, and they still have properties of that element Atoms-the smallest particle of an element that retains its identity in a chemical reaction. If you could line up 100,000,000 copper atoms in a single file, they would be approximately 1 cm long Not all atoms are created equal!

Structure of the Nuclear Atom Atoms are divisible into subatomic particles: Electrons, protons, and neutrons Electrons- negatively charged subatomic particles that surround the nucleus Protons-positively charged particles found in the nucleus of an atom Neutrons-subatomic particles with no charge and a mass nearly equal to that of a proton. Nucleus-tiny central core of an atom and is composed of protons an neutrons.