Matter and Energy Review Dustin Olivares 2016

 Draw an atom (structure) Identify the electrons, protons and neutrons  -draw Lithium

mass  How do you find the mass of an atom?  Its located at the bottom of the box.  Add protons and neutrons (They are located in the nucleus)

 Ex. Li  Do: Carbon, Neon, Na

Protons  How do you find the number of protons?  (+) positive sign  Same number as the atomic number and number of electrons  A tomic number  P rotons  E lectrons

 Ex. Li  Do: Carbon, Neon, Na

Electrons  How do you find the number of electrons?  (-) Negative sign  Located outside, in the shells, orbits, energy level, electron cloud.

 Ex: Li  Do: Carbon, Neon, Na

Neutrons  How do you find the number of Neutrons?  (+/-) Neutral sign  Located in the nucleus  Subtract the protons number from the mass  M- ass  A atomic number/number of protons  N eutrons

 Ex: Cl  Do: Carbon, Neon, Na

Valence Electrons  Valence electrons:  They determine an elements chemical properties, including reactivity.  Located: in the outer shell, orbit, energy level.  Groups (columns): 1 & 17 are the most reactive.

Valence electrons  The heavier the element the more reactive.  Weight increases going down and to the right in the periodic table.

 Ex: Li and F  Do: Na and Cl, K and Se, H and Be.

Periodic Table  Periodic Table:  Most groups (columns) tell you the number of valence electrons: 1, 2, 13-18

 Ex: 6 valence electrons, Carbon on group 16  Give me an example of 2 elements with 3 valence electrons  Give me and example of 2 elements with 1 valence electron  Give me and example of 2 elements with 7 valence electrons

 Groups (Columns): Elements share similar chemical properties.  Ex: Which of the following are Similar:  Ca, Sc, K, Mg  Do: Which of the following are Similar:  C, Ne, Kr, Xe, Li  Sr, Be, H, F, C

Period  Periods (Rows): same as the number of shells of an element.  Ex: Which element has 2 shells  Ca, H, Mg

Practice  Which element(s) has 1 shell?  Be, Li, H, He  Which element has 4 shells?  Be, Ca, Na, He

Chemical Formula  CHEMICAL FORMULAS  Purpose: to identify different substances, to be able to see their composition.  How do you know the composition? Locating Different elements and Counting the number of elements and atoms.

 How to find the number of elements: Count the Different elements  Ex:  NaCl  H 2 O  C 2 H 6 O 5

practice  Do:  3H 2 SO 4   C 6 H 12 O 6   C 2 OOH

 How to find the number of Atoms:  The coefficient multiplies everything, the Subscript multiplies the element right next to it, subscript also multiplies everything inside a parenthesis.

 Ex:  NaCl  H 2 O  C 2 H 6 O 5

 Do:  C 6 H 12 O 6   3H 2 SO 4   C 2 OOH (KCl) 3   3C 2 OOH (KCl) 3

 Are the following substances (chemical formulas) the same?  NaCl and NaCl  NaCl and KCl  2NaCl and NaCl  NaCl and NaCl 3

 Do:  3H 2 SO 4 and H 2 SO 4  C 6 H 12 O 6 and C 6 H 15 O 6  C 2 H 4 O 2 C 2 H 4 O 2

 BALANCED AND UNBALANCED CHEMICAL REACTIONS  Balanced: Both Sides have the same number of atoms (before and after)  By both sides I mean: reactants and products  Reactants: on the left  Products: on the right.  When the equation is balanced it follows the law of the conservation of mass.

 Ex:  2Ca+ O 2  2CaO   N 2 +3H 2  2NH 3  2Cu2O+ C  4Cu+CO2  2 H2O2  2 H2O + O2

 Do:  1. 2Na+MgF2  2NaF+Mg  2. Mg+ HCl  MgCl2 + H2  3. Cl2 + 2KI  KCl + I2

 Chemical reaction: It can’t go back.  Change in color: the products are a different color than the reactants.  Change in temperature: heat is released or absorbed during the reaction.  Production of a gas: gas bubbles are released during the reaction.  Production of a solid: a solid settles out of a liquid solution. The solid is called a precipitate.

 Give me more examples:

 Physical Reaction: It can go back  1. Ice melting involves a change from a solid to a liquid and the substances maintain the properties of water because the molecules never change.  2. Water boiling is a physical change as water molecules vibrate faster, they enter the gas phase and become water vapor.  3. Rubbing alcohol left uncovered will evaporate quickly into the air. It turns to a gas but maintains the properties of alcohol.

 4. Hot molten iron is a liquid and when left to cool will from solid steel and can take many forms.  5. Dissolving sugar in water is a physical change. The solid sugar never loses its properties, the molecules become separated by water and the sugar can easily be recovered by evaporating the water.

 Give me more examples.