Department of Petroleum and Mining General Chemistry Department of Petroleum and Mining First Stage 2017-2018 Wrea Mohammed Ibrahim

CHEMISTRY: (What is Chemistry?) Chemistry is the study of the properties, composition, and structure of matter, undergoes the physical and chemical changes, and the energy liberated or absorbed during those changes. Matter – anything that occupies space and has mass.

Classification of Matter: The basic difference between these states is the distance between the “bodies.” Gas – bodies are far apart and in rapid motion. Liquid – bodies closer together, but still able to move past each other. Solid – bodies are closer still and are now held in place in a definite arrangement.

Classification of Matter

The Law of Conservation of Matter : Matter is neither created nor destroyed during a chemical reaction or a physical change. ENERGY: Energy is the ability to do work or generate thermal energy.

Pure Substances and Mixtures: Mixture – combination of two or more substances in which each substance retains its own chemical identity. Homogeneous mixture – composition of this mixture is consistent throughout. Solution (Air, sugar water) Heterogeneous mixture – composition of this mixture varies throughout the mixture. Solution (blood, pizza)

Pure Substances and Mixtures It is also possible for a homogeneous substance to be composed of a single substance – pure substance. Element – A substance that can not be separated into simpler substances by chemical means. Compound - A substance composed of two or more elements chemically combined in fixed ratios by mass. Water - H2O Carbon dioxide - CO2 Sodium Chloride – NaCl Iron(II) sulfide - FeS Atom – the smallest unit of an element that retains a substances chemical activity.

Elements There are 114 elements known. Each element is given a unique chemical symbol (one or two letters). Carbon C, Nitrogen N, Titanium Ti Notice that the two letter symbols are always capital letter then lower case letter because: CO – carbon and oxygen Co – element cobalt

Classification of Mixtures: - Homogeneous - A mixture having only one phase; it is uniform (the same) throughout and has the same properties throughout. These are called Solutions. - Heterogeneous - A mixture with more than one phase. It is non-uniform and does NOT have the same properties throughout. Lecture Notes

Matter and Change Physical Change - A change in which each substance involved in the change retains its original identity and no new elements or compounds are formed. H2O (s) H2O (l) Melting Point Boiling Point Temperature Density Mass Volume Melting Lecture Notes

Physical Change

Chemical Change -A change in which one or more elements or compounds (substances) are formed. AgNO3 (aq) + HCl (aq) AgCl (s) + HNO3 (aq) “Reacting” Lecture Notes

Properties of Matter Extensive Properties - Properties that depend on the amount of matter present in a sample. Mass Volume Heat Capacity Intensive Properties - Properties that do NOT depend on the amount of matter present in a sample. Color Temperature Density Melting Point Specific Heat Boiling Point Lecture Notes

All matter is made up of undividable particles called atoms. Atoms are completely solid. Atoms are homogeneous. Atoms vary in: 1)Size 2) Shape 3) Weight

…Dalton’s Research… 1.Chemical elements are made of atoms 2.The atoms of an element are identical in their masses. 3. Atoms of different elements have different masses.

The charges of the parts in an atom are shown for a oxygen atom. Pictures of an atom The green and red spheres represent the protons and neutrons of the atom. The orange spheres represent the electrons. The charges of the parts in an atom are shown for a oxygen atom.

Key Definitions of Today’s Atom Proton – positive part of the atom; found in the center of the atom (nucleus) Neutron – neutral (no charge) part of the atom; found in the center of the atom Electron- negative part of the atom; found circling the center of the atom Nucleus – center of the atom; home of the proton and neutron; has the majority of the mass of the atom

An ion forms when an atom gains or loses one or more electrons. Ions: An ion forms when an atom gains or loses one or more electrons. positive ions -formed when atoms lose electrons negative ions -formed when atoms gain electrons

Element: A substance composed of only one type of atom (all the atoms have the same number of protons). Elements cannot be broken down into smaller substances. Molecule: A unit composed of two or more atoms joined together by chemical bonds

Molecular mass or Molecular weight Is the mass of a molecule. It is calculated as the sum of the atomic mass of each constituent atom multiplied by the number of atoms of that element in the molecular formula. Example:- H2O , CO2 M.wt H2O = (2*1 )+(1*16) =18 g/mole M.wt CO2 = (1*12)+ (2*16)= 44 g/mole