Chapter 21-physics SHORTENED

Chapter 21:Atomic Structure & interactions : 

Chapter 21:Atomic Structure & interactions By: Ashley Zangla Oslynne Buckner Johanna Vega

Internal Structure of the Atom: Key Concepts : 

Internal Structure of the Atom: Key Concepts What is an Atom? Atom- the smallest particle that retains its chemical identity. In 1897, English physicist Joseph John Thomson identified a particle called the electron. Electron- A subatomic particle with negative charge and small mass Atoms are not the fundamental building blocks of matter, but they are made up of particles that are smaller and more fundamental still.

Parts of an Atom : 

Parts of an Atom

The Atomic Nucleus : 

The Atomic Nucleus Ernest Rutherford physicist discovered the structure of an atom. Rutherford used radioactive material, which is matter that sends out energetic particles for his experiment called alpha particles. Alpha particles- positively charged particles thousands of times heavier than electrons.

Rutherford’s Experiment : 

Rutherford’s Experiment The experiment was designed to measure something about the way atoms are put together. Experiment result: all of the bullets except a few passed straight through the spaces in between the gold atoms, of the gold foil. Some also bounced straight back.

Slide 6: 

Rutherford concluded that a large part of each atom’s mass is located in a very small, compact object at the center, which he called the nucleus. Nucleus- a very small dense, positively charged object at the center of every atom; nuclei are made up of protons and neutrons.

The Ground State and Excited State : 

The Ground State and Excited State · An electron in the lowest energy level is said to be in the ground state. · All energy levels above the ground state are called excited state

Spectroscopy : 

Spectroscopy When energy is added to a system with many atoms in it, electrons in some atoms jump to exited states also when that happens it gives out photons and if some are in the range of light, they appeared to glow.

Slide 9: 

Electrons energy levels depend on the electrical attraction between the nucleus and electrons. Different nucleus have different number of protons, so electrons circling them are in different levels. The energies between allowed energy levels within atoms, The total collection of photons emitted by a given atom is called a spectrum. Each possible quantum jump corresponds to light at a specific wavelength

Slide 10: 

3 Examples of how wavelengths work. If the white light shines through a material containing a particular kind of atom, then certain wavelength of light are absorbed. When you absorbed the light on the other side of the material, then certain lines of color are missing. The dark areas corresponding to the absorption lines and they are as much an atom fingerprint as the set of colors that glowing emits. Spectroscopy is used by many astronomers, they use the emission spectra to determine the chemical composition of distance stars.distance stars

The Laser : 

The Laser The action of a laser. Electrons in the laser’s atoms are continuously pumped into an exited state by an outside energy source, and the beam of coherent photons is released when the electrons return to their ground state. The mirror from where the beam reflects is designed to be practically reflective 95% of the atoms that hit the mirror are reflected back into the laser. The remaining 5% of photons that leak out form the familiar laser beam.

Periodic Table of Elements : 

Periodic Table of Elements Dmitri Mendeleev, A Russian scientist developed the periodic table in the 19th Century Systematizes all known chemical elements, provides the framework for understanding the structure and interaction of atoms

Slide 16: 

The periodic table organized 63 elements when it was first written down by Mendeleev. In the original table there were holes, places where he predicted elements should go

Atomic Number : 

Atomic Number The Atomic number corresponds to the number of protons in the atom, or, equivalently. If the atom is not charge, to the number of electrons surrounding the nucleus

Why the periodic table works:Electron Shells : 

Why the periodic table works:Electron Shells The pattern of elements in the periodic table mirrors the spatial arrangement of electrons around the atom’s nucleus -The electrons are arranged into shells When two atoms come near enough to one another to undergo a chemical reaction electrons in the outermost shells meet one another first - such as a carbon atom and a oxygen atom in a burning piece of coal

Understanding the Periodic Table : 

Understanding the Periodic Table These outermost electrons govern the chemical properties of materials

Pauli Exclusion Principle : 

Pauli Exclusion Principle No two electrons in an atom can occupy the same state at the same time -once an electron fills a particular space in the atom no other electron can occupy the same space

Electron Shell : 

Electron Shell There are only two spaces that an electron can fill in the inner most electron shell - corresponds to the lowest Bohr energy level

Slide 24: 

Hydrogen with a single electron in the innermost shell, and helium with two electrons in that same shell. If we want to add one more electron, it has to go into the second electron shell because the first electron shell is completely full. - explains why only hydrogen and helium appear in the first row of the the periodic table

Slide 26: 

The second electron shell has room for eight electrons, a fact reflected in the eight elements of the periodic table’s second row - Neon appear directly under helium, and we expect these two element to have similar chemical properties because both have a completely full outer electron shell

Predicting Chemical Formulas : 

Predicting Chemical Formulas The periodic table tells you how many electrons are in the outer shell of each element. Atoms are usually more stable with a completely filled outer shell of electrons Elements at the left in the periodic table usually donate electrons

For more infromation about what we have discussed : 

For more infromation about what we have discussed - The Ruthford Model http://www.youtube.com/watch?v=FfY4R5mkMY8&feature=related -The bohr Model http://www.youtube.com/watch?v=hpKhjKrBn9s&annotation_id=annotation_736168&feature=iv -Spectra http://www.youtube.com/watch?v=5z2ZfYVzefs&feature=related

Slide 30: 

Proton, Nuetrons, & Electrons http://www.youtube.com/watch?v=-P4N-0Wbtyk&feature=related