NOTE: This presentation was not made for public use. Please do not use this presentation without my permission and the permission of each of the authors of the photographs, quotes, and other materials that they contain. Thank you, Vicki Hughes Labs and Activities that go with this presentation: Let’s Get Chemical

Chemistry is the study of elements. Elements are made of atoms. Elements = natural substances that cannot be broken down into simpler substances. Which one of these items is an element? X ATOMS AND ELEMENTS

Alchemy = Chemistry Gold was the most fascinating element during the middle ages.

Atoms are measured in nanometers (nm). Each atom has mass and takes up space. Atoms are measured in nanometers (nm). Each atom has mass and takes up space. All matter is made up of individual particles called atoms, which cannot be divided. John Dalton You Can’t Touch Anything 5:29

Matter is anything that has mass and occupies space. All matter is made of atoms. Atoms are the smallest form of elements. About 100 elements Hydrogen is an element that accounts for about 90% of total mass of the universe. Hydrogen makes up about 1% of Earth’s crust and most of that is in water.

All of an atom’s positive charge is concentrated in the nucleus. Ernest Rutherford

Structure of an Atom Proton = positive charge Neutron = no charge The number of protons and neutrons varies with each element, however they are usually equal to each other. Electron = negative charge Protons and neutrons are grouped together in the nucleus. (Atomic Mass) e- Electrons are located outside the nucleus and are in motion. e-

Atomic Mass = protons + neutrons # of Neutrons = Mass Number – Atomic Number Atomic Mass? = 12 # of electrons? 6 protons balanced by 6 electrons Atomic Mass? = 12 # of electrons? 6 protons balanced by 6 electrons Atomic Number = Number of protons

ISOTOPES: variations of an element Have a different number of neutrons but same number of Protons Designated by the name of the element and its atomic mass number. Normal carbon nucleus (ACT L6 and EOG L1)

Dimitri Mendeleev I have created a periodic table where the elements are arranged according to their number of protons. This puts elements with similar properties in the same column. Yes, clearly I am a genius! Just watch this… SciShow Mendeleev’s Perioidc Table wu0LixSBpk&list=UUZYTClx2T1of7BRZ86-8fow

The PERIODIC TABLE organizes the atoms of the elements by properties and atomic number. Atomic Numbers PERIODIC TABLE OF THE ELEMENTS

There are over 100 elements in nature. The Periodic Table is divided into metals, metaloids and nonmetals. METALS METALOIDS NONMETALS Warning: Some periodic tables are not color=coded!

Group – elements in a column with similar chemical and physical properties. Period – horizontal rows. Shows progression of the chemical properties of the elements. GROUP PERIOD

GROUP PERIOD Elements on the left of a period have a lower atomic mass than elements on the right of a period. Elements at the bottom of a group have more protons than elements at the top of the group.

Properties of Metals, Metaloids, & Nonmetals METALS METALOIDS NONMETALS

Each element has a symbol that is used only for that element. C Symbol Symbols you should know: Co = cobalt C = carbon O = oxygen N = nitrogen H = hydrogen Cr = chromium Cs = cesium Mg = magnesium Na = sodium Cl = chlorine Pb = lead K = potassium Symbols you should know: Co = cobalt C = carbon O = oxygen N = nitrogen H = hydrogen Cr = chromium Cs = cesium Mg = magnesium Na = sodium Cl = chlorine Pb = lead K = potassium

Each element has a box that provide information about that element. C Atomic # Atomic Mass Symbol

How do you calculate the number of neutrons? Neutrons = Atomic Mass – Atomic Number C Atomic # Atomic Mass

Bohr-Rutherford Diagrams Bohr-Rutherford diagrams are a special type of illustration that shows the arrangement of the electrons around an atomic nucleus. Octet Rule states that no more than 8 electrons will be assigned to any shell. Neils Bohr

Bohr-Rutherford Diagrams 1.Draw the nucleus as a circle.

Put the number of protons (atomic number) and neutrons (mass number - # of protons) in the nucleus. P=19 N=20 39 – 19 = 20

The electrons are in shells (levels) around the nucleus. 1st Shell = 2 electrons3rd Shell = 18 electrons 2nd Shell = 8 electrons4th shell = 32 electrons P=19 N=20

Draw the electrons by adding shells (circles) around the nucleus. The first shell has only 2 electrons. But the remaining shells usually have no more than 8 electrons. P=19 N=20 e- e-

Practice drawing Bohr diagrams for these elements: Calcium (Ca) Nitrogen (N) Oxygen (O) Carbon (C)

ELECTRON CONFIGURATION Valence Electrons = electrons in outermost shell.

Lewis Structures Show the valence electrons in an atom – just the outmost level N Drawing Lewis Dot Diagrams

Lewis Structures H O H O H H

Practice drawing Lewis structures for these elements: Calcium (Ca) Nitrogen (N) Oxygen (O) Carbon (C) POP! Bohr & Lewis

Atoms are NEUTRAL if they have all of their electrons. Carbon is neutral if it has 6 electrons. C Atomic # Atomic Mass

Noble gases -- Group 8 have full electron shells least likely to combine with other elements

NaCl Who will lose and who will gain an electron? + Atoms gain electrons (negatives) and become more negative. Atoms with 2-3 valence electrons will LOSE electrons and become more positive. MOLECULES, COMPOUNDS, and CRYSTALS (EOG L3)

Atoms have no overall electrical charge. Ions have charges because they have gained or lost an e-. x Lost 1 e- Became positive _ + Gained 1 e- Became negative

Molecular hydrogen (H 2 ), molecular oxygen (O 2 ) and molecular nitrogen (N 2 ) are not compounds because each is composed of only one kind of element. Molecule = two or more atoms join together chemically. Compound = molecule with at least two different elements. H-H O=O : : :: : : N=N : : = This is a molecule, but… …it is NOT a compound!

Water (H 2 O), carbon dioxide (CO 2 ) and methane (CH 4 ) are compounds because each is made from more than one element. O H H O=C=O : : : : This is a molecule, AND… …it is also a compound!

The smallest bit of each of these substances would be referred to as a molecule. One water (H 2 O) molecule ACT L7 (1-4 only) EOG L2

Element, Molecule, Compound, or Isotope? 1. water 2. carbon dioxide 3. oxygen gas (O2) 4. helium 5. carbon with an atomic mass of carbon with an atomic number of 6 7. carbon with 8 neutrons 8. carbon with an atomic mass of 14

A mixture is matter made up of two or more substances that combine physically only. Trail Mix In Heterogenous Mixtures substances are not distributed evenly throughout the mixture. Cup of Lucky Charms. MIXTURES sALAD GRANITE

Mixin ’ It Up! In Homogenous Mixtures substances are distributed evenly throughout the mixture. Mustard, Ketchup, small cup, stirrer AIR steel CLEAR SALT WATER

Mixin ’ It Up! Solutions are homogenous mixtures in which one substance dissolves completely into the other. Solvent is the substance that does the dissolving. Solute is the substance that gets dissolved. Drink mix, water, cup, stirrer

Separation Anxiety! How do you separate mixtures? Sifting = separation by particle size.

Separation Anxiety! How do you separate mixtures? Filtration = separating a solid from a liquid in a heterogenous mixture. Filtration = separating a solid from a liquid in a heterogenous mixture.

Separation Anxiety! How do you separate mixtures? Evaporation = separating a solid from a liquid in a solution.

Boiling Point = point at which matter changes from a liquid to a gas. Melting Point = point at which matter changes from a solid to a liquid. Freezing Point = point at which matter changes from a liquid to a solid. Do you know what “dry ice” really is? Solid CO 2 ! Physical Properties PHYSICAL AND CHEMICAL CHANGES

Shape = physical limitations. Odor = aroma of substance. Color = reflection of light. Solubility = measure of the ability to dissolve in another substance (Solute is what is being dissolved and the Solvent is what is doing the dissolving) PHYSICAL Properties of Matter

Conductivity = ease with which electrons move through the material. Magnetism = ability to be attracted or repelled by another materials due to a magnetic field. Malleability = ability to be hammered or rolled into sheets. Ductility = ability to be pulled and stretched into wire. Polarity = arrangement of atoms

Density = amount of mass contained in a unit volume. 1. Regularly-shaped objects use a ruler and a balance and D=m/v 2. Irregularly-shaped objects use a graduated cylinder and a balance and D=m/v 3. Liquids are compared with other liquids. PHYSICAL Properties of Matter

Ways to Change Matter Density decreases as temperature increases! Increasing Heat

Ways to Change Matter Motion of particles increases as temperature increases! Increasing Heat

Reactivity = ability of a material to combine with or change into another substance. Reacting to oxygen (burning) Reacting to acids pH = acidity or basicity Combustibility = tendency to burn CHEMICAL Properties of Matter

What is a chemical reaction? A chemical reaction is the change of a substance into a new one that has a different chemical identity. How can I tell if a chemical change is occurring? emission of light a change in temperature formation of a precipitate (a solid substance that settles to the bottom) evolution of a gas a color change =gs0j1EZJ1Uc Glowsticks

Properties of Matter Chemical ChangesPhysical Changes

Any Questions? EOG L4 & L5