Matter and Chemical Bonding
All non zero integers are significant ~ 456cm
All zeros to the left of the first non zero digit are not significant~ 0.005kg All zeros between non zero digits are significant~ 207.08 km All zeros at the end of a number that has a decimal point are significant ~ 34.070 mg Density
Density is a physical property of matter, as each element and compound has a unique density associated with it. Density defined in a qualitative manner as the measure of the relative "heaviness" of objects with a constant volume.
A substance with uniform composition. Cannot be separated by physical or mechanical means. Elements
Cannot be broken down or changed into another substance using chemical means. *Building blocks of matter* Compounds
A pure substance that is composed of two or more elements chemically combines in fixed proportions Mixtures
A combination of two or more kinds of matter, in which each component retains its own characteristics Heterogeneous
A mixture in which the different components can be distinctly seen Homogeneous
A mixture in which the different components are mixed so that they appear to be a single substance; a solution Physical Properties
Reactivity with water
Reactivity with air
Reactivity with pure oxygen
Reactivity with acids
Reactivity with pure substances
Refers to how close a given quantity is to an accepted or expected value Precision
Refers to the exactness of a measurement or the closeness of a series of data points Atomic Theory of Matter
John Dalton described atoms as solid, indestructible particles that make up all matter. All matter is made up of tiny particles called atoms. An atom cannot be created, destroyed or divided into smaller pieces. The atoms of one element cannot be converted into the atoms of any other elements All the atoms of one element have the same properties such as mass and size. These properties are different from the properties of the atoms of any other element. Atoms of different elements combine in specific proportions to form compounds
Mass number = number of protons + number of neutrons
Atomic number = number of protons
Atoms of an element that have the same number of protons but different numbers of neutrons Periodic Table Trends
Types of Chemical Bonds
Ionic Bond : formed when one atom accepts or donates one of its valence electrons to another atom Covalent Bond: formed when atoms share valence electrons. The atoms do not always share electrons equally, so a polar covalent bond may result. Metallic Bond: when electrons are shared equally by two metallic atoms. The electrons that participate in metallic bonds may be shared between any of the metal atoms in the region. If the electronegativity values of two atoms are:
Characteristics of Metallic Bonds:
Heat conductivity (mobile electrons can carry the kinetic energy of heat), Shiny appearance (the rapidly moving electrons emit energy in the form of light), Electricity conductors (electricity is the flow of electrons), and Malleability (ability to be easily shaped into flat sheets or drawn into wires). similar...
Metallic bonds form between two metal atoms.
Covalent bonds form between two non-metal atoms.
Non polar covalent bonds form when the electronegativity values are very similar. Polar covalent bonds form when the electronegativity values are a little further apart. different...
Ionic bonds are formed.
Properties of Ionic and Covalent Compounds
State at room temperature
Liquid, gas, solid
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