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Atomic structure

Atomic structure. Mrs. Selent. Matter. Anything that occupies space and has mass. Mass is the quantity of matter an object has (how much there is) Mass and weight are different, the same mass will have different weights on different planets. Weight is determined by gravity. Atomic Structure.

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Atomic structure

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  1. Atomic structure Mrs. Selent

  2. Matter • Anything that occupies space and has mass. • Mass is the quantity of matter an object has (how much there is) • Mass and weight are different, the same mass will have different weights on different planets. • Weight is determined by gravity.

  3. Atomic Structure • Atom – the smallest unit of matter that cannot be broken down by chemical means.

  4. ELECTRON – negative, mass nearly nothing NEUTRON – neutral, same mass as proton (“1”) PROTON – positive, same mass as neutron (“1”) The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: The structure of the atom Dalton

  5. The Atom Electron (- charge) Nucleus (+ charge) Electron Cloud

  6. Electrons • Electrons have 1/1840 the size of a proton. • They are in constant motion around the nucleus. • The speed and energy of their motion prevent them from being pulled into the nucleus. • They are arranged into energy levels, were each level can hold a specific number of electrons. • Protons and electrons are attracted to one another because of their opposite charges. • Typically there is one electron for each proton causing an atom to have no electrical charge.

  7. How shells fill • The first energy level can only hold a maximum of two electrons. • The second energy level can hold a maximum of eight electrons. • The third energy level can also hold a maximum of eight electrons. • The fourth energy level can also hold eighteen electrons.

  8. 19 K 39 Nucleus Electron structure Consider an atom of Potassium: Potassium has 19 electrons. These are arranged in shells… The inner shell has __ electrons The next shell has __ electrons The next shell has __ electrons The next shell has the remaining __ electron Electron structure = 2,8,8,1

  9. Elements • An element is a pure substance made of only one kind of atom. • Out of all the elements about two dozen (24) of them are commonly found in living organisms. • The Periodic Table is an organized list of known elements.

  10. MASS NUMBER = number of protons + number of neutrons 2 He SYMBOL 4 PROTON NUMBER = number of protons (obviously) Mass and atomic number

  11. How many protons, neutrons and electrons? 1 5 8 H B O 1 11 16 11 17 92 Na Cl U 23 35 238

  12. If You Change The • Protons – you change the atom • Neutrons – you change the mass of the atom and thus the stability of the atom • Electrons – you change the charge of the atom.

  13. Isotopes • Isotopes are atoms of the same element that differ in the number of neutrons they contain • Identified by their mass number, which equals the number of protons and neutrons in the nucleus. • Carbon-12, Carbon-13, and Carbon-14 each contain 6 protons. • Because they have the same number of protons all isotopes of an element have the same chemical properties.

  14. Atomic Bonding • Chemical bond is a force that holds atoms together. • Compound is a substance formed by the chemical combination of two or more elements. • Ex. Sodium (Na) and Chlorine (Cl) combine to form NaCl – table salt

  15. Atomic Bonding • Every compound is represented by a chemical formula that identifies the elements in the compound and their proportions. • NaCl = 1 sodium atom and 1 chlorine atom • H2O = 2 hydrogen atoms and 1 oxygen • The physical and chemical properties of compounds are usually very different from the elements it is composed of

  16. Covalent Bonds • Bond formed when two or more atoms share electrons to form a molecule. • The shared electrons travel in the orbits of both atoms. • Usually occur between two non-metals

  17. Molecule • The smallest unit of most compounds • Elements that are covalently bonded. • If the number of protons is equal to the number of electrons there is no electrical charge. Ex. CO2 or O2 • The arrangement of electrons determines how the atoms bond together. • Atoms will react readily with atoms that can provide electrons to fill the outer electron level.

  18. Ionic Bond • Bond formed when one or more electrons are transferred from one atom to another. • Ion – an atom or molecule that has gained or lost one or more electrons • Ions have an electrical charge and interact to form ionic bonds. • Usually occur between a metal and a non-metal • Na + + Cl- = NaCl

  19. The Nobel gases • The Nobel gases have full outer shells and they are found in group 8 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.

  20. The Atom Neon Electrons Protons Neutrons Neon has ten electrons, ten protons and ten neutrons.

  21. The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Mendeleev Periodic table Horizontal rows are called PERIODS

  22. These elements have __ electrons in their outer shell E.g. all group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shells The Periodic Table Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number)

  23. E.g. Lithium has 3 electron in the configuration 2,1 Sodium has 11 electrons in the configuration 2,8,1 Potassium has 19 electrons in the configuration __,__,__ The Periodic Table Fact 2: As you move down through the groups an extra electron shell is added:

  24. These elements are metals This line divides metals from non-metals These elements are non-metals The Periodic Table Fact 3: Most of the elements are metals:

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