Objective 4 Chemistry

Chemistry

The Basics Matter – Anything that has mass and takes up space Substances – Cannot be broken down Physically Mixtures – physical combination of two or more substances

Substances Elements Cannot be broken down any farther Found on the Periodic Table Compounds Chemical combination of two or more elements Requires a chemical reaction to separate III IV V VI VII Hg Cd H Li Na K Rb Cs Be Mg Ca Sr Ba Ra Sc Ti V Cr Mn Fe Co Ni Cu Zn B C N 1s1 O F Ne He 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14 Al Si P Cl Ar Ga Ge As Se Br Kr In Sn Sb Te I Xe Tl Pb Bi Po At Rn Y Zr Nb Mo Tc Ru Rh Pd Ag La Hf Ta W Re Os Ir Pt Au Ac Rf Db Sg Bh Hs Mt 5f1 5f2 5f3 5f4 5f5 5f6 5f7 5f8 5f9 5f10 5f11 5f12 5f13 5f14 I A II A A VIII III IV V VI VII VIII I II

Mixtures Homogeneous Uniformly mixed Heterogeneous Unevenly mixed Like soda Heterogeneous Unevenly mixed Like tossed salad

Properties of matter Physical Describes how something looks or feels Observed using the senses Example: color, texture, States of matter are physical properties Chemical Describes how something acts (or reacts) Observed through chemical reactions Examples: being flammable, iron will rust

Physical Properties Extensive Intensive Does depend on how much you have Examples: mass, volume, Intensive Do not depend on how much of something you have Examples: color, shape, density

Changes in Matter Physical Chemical Any change that does not alter the chemical make up of a substance Example: Tearing paper Boiling water Melting iron There are three main states of matter: solid, liquid, gas Changing from one state to another is a physical change does not change the substance Chemical Any change in matter that does alter the chemical composition of a substance Examples: Burning wood Vinegar and baking soda Rusting iron

The Atom Protons Neutrons Electrons The atom is the smallest part of an element that still retains the properties of that element. All atoms are made up of three subatomic particles Protons Positive charge Located in nucleus Mass of 1 Neutrons No charge Electrons Negative charge Located in electron cloud surrounding nucleus Mass of 0

The Atom An element is defined by the number of PROTONS it has Protons + Neutrons + Mass. In a neutral atom, the number of protons and electrons is the same Atoms of the same element can differ in the number of electrons or the number of neutrons

Isotopes Atoms of the same element with different numbers of neutrons are called isotopes. In isotope notation (carbon-14) the number tells the total atomic mass.

IONS Atoms of the same element with different numbers of electrons are called ions The charge of an ion is always written as a superscript (Na+1) If an ion has a positive charge, then it has LOST electrons If an ion has a negative charge, then it has GAINED electrons

The Periodic Table III IV V VI VII Hg Cd H Li Na K Rb Cs Be Mg Ca Sr Ba Ra Sc Ti V Cr Mn Fe Co Ni Cu Zn B C N 1s1 O F Ne He 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14 Al Si P Cl Ar Ga Ge As Se Br Kr In Sn Sb Te I Xe Tl Pb Bi Po At Rn Y Zr Nb Mo Tc Ru Rh Pd Ag La Hf Ta W Re Os Ir Pt Au Ac Rf Db Sg Bh Hs Mt 5f1 5f2 5f3 5f4 5f5 5f6 5f7 5f8 5f9 5f10 5f11 5f12 5f13 5f14 I A II A A VIII III IV V VI VII VIII I II The periodic table organizes the elements by their chemical properties and reactivity.

The Periodic Table III IV V VI VII Hg Cd H Li Na K Rb Cs Be Mg Ca Sr Ba Ra Sc Ti V Cr Mn Fe Co Ni Cu Zn B C N 1s1 O F Ne He 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14 Al Si P Cl Ar Ga Ge As Se Br Kr In Sn Sb Te I Xe Tl Pb Bi Po At Rn Y Zr Nb Mo Tc Ru Rh Pd Ag La Hf Ta W Re Os Ir Pt Au Ac Rf Db Sg Bh Hs Mt 5f1 5f2 5f3 5f4 5f5 5f6 5f7 5f8 5f9 5f10 5f11 5f12 5f13 5f14 I A II A A VIII III IV V VI VII VIII I II On this table, the colors show the groups (families). Elements in the same column have similar chemical properties.

The Periodic Table III IV V VI VII Hg Cd H Li Na K Rb Cs Be Mg Ca Sr Ba Ra Sc Ti V Cr Mn Fe Co Ni Cu Zn B C N 1s1 O F Ne He 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14 Al Si P Cl Ar Ga Ge As Se Br Kr In Sn Sb Te I Xe Tl Pb Bi Po At Rn Y Zr Nb Mo Tc Ru Rh Pd Ag La Hf Ta W Re Os Ir Pt Au Ac Rf Db Sg Bh Hs Mt 5f1 5f2 5f3 5f4 5f5 5f6 5f7 5f8 5f9 5f10 5f11 5f12 5f13 5f14 I A II A A VIII III IV V VI VII VIII I II All Elements to the LEFT of the stair step line (red line) are metals. Elements to the RIGHT are nonmetals. Elements that are touching the line are called metalloids or semi-metals

The Periodic Table The groups are named as follows: III IV V VI VII Hg Cd H Li Na K Rb Cs Be Mg Ca Sr Ba Ra Sc Ti V Cr Mn Fe Co Ni Cu Zn B C N 1s1 O F Ne He 4f1 4f2 4f3 4f4 4f5 4f6 4f7 4f8 4f9 4f10 4f11 4f12 4f13 4f14 Al Si P Cl Ar Ga Ge As Se Br Kr In Sn Sb Te I Xe Tl Pb Bi Po At Rn Y Zr Nb Mo Tc Ru Rh Pd Ag La Hf Ta W Re Os Ir Pt Au Ac Rf Db Sg Bh Hs Mt 5f1 5f2 5f3 5f4 5f5 5f6 5f7 5f8 5f9 5f10 5f11 5f12 5f13 5f14 I A II A A VIII III IV V VI VII VIII I II The groups are named as follows: Alkali metals Alkaline-earth metals Transition metals Inner-transition metals Halogens Noble gases

Chemical Bonds Ionic Bonds Covalent Bonds A Chemical bond is the force that holds two atoms together Bonds form so that atoms can be stable. An atom is stable when it has eight valence (outside) electrons The noble gases have eight valence electrons and therefore do not react with other elements The Two types of chemical bond are: Ionic Bonds Covalent Bonds

Ionic Bonds Formed when one atoms gives up electrons and another one takes them Called ionic because ions are formed Form crystals in solid form Have much higher melting and boiling points Example : NaCl……. Table salt

Covalent Bonds Formed when one atom shares it electron with another The word “covalent” means “outsides together” Generally do not form crystals Have lower boiling and melting points Example: H2O ….. Water

Chemical Reactions How do you know a chemical reaction has happened? It gives off light (flames are a good sign) It gives off or absorbs heat (again with the flames) It changes colors (unexpectedly) Produces a gas (usually observed as bubbles or fizz) Produces a precipitate (a solid formed from two liquid reactants)

What are the different types of chemical reactions? Synthesis – only one product from more than one reactant Decomposition – more than one product from only one reactant Single replacement – an element replaces one element in the other reactant Double replacement – The two compounds that react trade partners Combustion – must have oxygen, usually gives off a large amount of heat

1 CaSO4 + 2 LiOH  1 Li2SO4 + 1 Ca(OH)2 Chemical Equations A chemical equation uses symbols and chemical formulas to represent what happens in a chemical reaction. They look like the following: 1 CaSO4 + 2 LiOH  1 Li2SO4 + 1 Ca(OH)2 Reactants Products Subscripts Coefficients