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Chapter 18 Atoms and Elements 18.1 Atomic Structure Goals *What are the parts of an atom? *How did the work of numerous scientists lead to the current model of an atom? I. All matter (everything you see, hear, touch, smell and taste) is formed from __________, either by themselves or combined in _______________. A. Size 1. Atoms are tiny!!! A dust speck contains more than___________. B. Parts 1. Atoms contain _____ __________ particles: they are: __________________________ 2. Nucleus- ____________________ ___________________. 3. The _______________ move in space around the nucleus. Their location ___________ be determined at any one time. C. Subatomic particles have charge and mass: Particle Charge Mass (amu) So...how did we find all this out? II. Scientists Involved A. Greek Philosophers- proposed an atomic theory around 400 BC which stated....all matter is made __________________________ ______. B. Democritus- Named the atom from the Greek word _______, meaning "____________". C. 1. John Dalton's Atomic Theory (1808) Elements are made of ___________ 2. Atoms of the same element are ____________. 3. Atoms of __________________________. 4. Atoms are ____________ by chemical reactions. 5. Compounds are formed by joining ___________. 6. Compounds are defined by number, type and proportion of atoms. D. Joseph John Thomson (1904) 1. Discovered the ___________ and determined that they have a ____________charge. 2. He knew that atoms were ___________, so proposed that the atom was a ___________ with negative electrons embedded in it. E. Ernest Rutherford (1911) 1. Conducted the "______________" experiment. 2. Hypothesized that atoms are made _________ ________________________ 3. Introduced the nucleus- ________________. F. Niels Bohr (1885- 1962) 1. Conducted experiments to update Rutherford's model. 2. Stated that ____________ move around the nucleus in ____________ G. James Chadwick (1932) 1. Discovered the _______________ 2. Introduced the __________________ _____________________________. 3. The cloud represents _________ location of an electron. Comparing Atoms Goals: * What is the difference between atomic number, mass number and atomic mass? *How do we create an accurate atom diagram of any element? How is an isotope diagram different? A. Atomic Number 1. The atomic number is the number of _______________________ 2. The atomic number ___________ the type of element you have. Ex. 7 protons= _____________ 15 protons= _____________ ALWAYS!! 3. The periodic table is ordered by the number of ________________. *It starts with 1 (hydrogen) and ends with 118 (ununoctium) B. Mass Number vs. Atomic Mass 1. Mass number- the total number of _______________ (in the nucleus). * Atoms of the same element ________ have different number of ___________, which means the mass can vary. 2. Atomic Mass- the average of ________________ of an element. A i m to c ss a m The mass number would be 31 C. Isotopes 1. Isotope- ________ of the same element that have _________________________. Example: Carbon Carbon-12 Carbon-13 protons= neutons= D. Strong Nucleus Force The nucleus contains positive protons and neutral neutrons, so what holds it together? It is held together by __________ ________________________ ...called the strong ______________. E. Energy Levels 1. Electrons are arranged into _____________ that hold a specific amount of electrons. 2. The energy levels make up the electron cloud. 3. The ___________ out the electrons are, the _______ their energy state. 4. ____________ electronselectrons in the _________ region of the electron cloud- the _________ involved in bonding.