1. Atom The smallest particle of an element that still has the properties of that element

no electrical charge positive charge center of atom negative charge

2. Compound Made of combination of elements Properties of compounds often differ from properties of elements that make them up

hydrogen= H carbon= C + C6H12O6 oxygen= O + =

6 carbon atoms 12 hydrogen atoms 6 oxygen atoms ex. C6H12O6 = glucose (sugar) 6 carbon atoms 12 hydrogen atoms 6 oxygen atoms

3. Atomic Theory – the beginning Democritus believed that the tiniest particle was the atom, which was the smallest thing that could ________________________________. He also thought that atoms were made of a _________________________________ that formed into different shapes and sizes. be divided to single material Atomos  indivisible

4. John Dalton’s Atomic Theory Based on scientific _________________________ through __________________, John Dalton published a theory in 1803. His theory states these ideas: evidence experiments

4. John Dalton’s Atomic Theory All substances are made of ________________. Atoms are small particles that cannot be ________________, __________________, or _________________________. Atoms of the same element are ________________________________. and the atoms of different elements are ___________________________. Atoms join with other atoms to make ______________________________. atoms created divided destroyed exactly alike different. new substances

5. Disagreeing with Dalton As scientists were able to gather new data, more discoveries about the atom showed some mistakes with Dalton’s theory.   J. J. Thompson discovered with a __________________________ that atoms contained ___________________-charged particles called ___________________. He came up with the ______________________________ model. cathode-ray negatively electrons. Plum-pudding

6. Rutherford’s Atomic Discoveries Later, one of Thompson’s students named Ernest Rutherford discovered the ________________________-charged particles in the center of the atom. . positively

6. Rutherford’s Atomic Discoveries Gold-foil He designed the _____________________ experiment. .

7. Bohr’s Model and Modern Theory With more experiments and evidence, Niels Bohr developed his model named after himself, called the ________________ model.  This model represents a small, positively-charged __________________ surrounded by _____________________ that travel in _________________________________ around the nucleus. Bohr nucleus electrons circular orbits

7. Bohr’s Model and Modern Theory Modern Theory developed by scientists, especially Schrödinger and Heisenberg, states that electrons are found in probable ______________________________ called __________________________________. regions Electron clouds

Now let’s draw the models that evolved throughout history.