Matter that has Chemical and Physical Properties

• Matter has many forms

  • matter - anything that has mass and volume

  • mass is a measure of quantity of an object (g, kg)

  • volume is a measure of space taken up (mL, L)

  • mater can be found as a solid, liquid, or gas (can also be a combination)

• The Particle Theory of Matter

  • 1. All matter is composed of very tiny objects called particles

  • 2. Each pure substance unique particles

  • 3. Particles present in matter are always in motion

  • 4. The particles in a substance attract each other

Classification of Matter

• PURE SUBSTANCES

  • pure substances: only made up of 1 kind of matter

    • unique set of properties

      • color, hardness, boiling point, etc

        a pure substance is either an element (gold) or a compound (sugar)

  • elements are a pure substance that cannot be broken down into any simpler substance by chemical means

    • each element has its own symbol and name (gold (Au))

  • compounds are a pure substance that is made from 2 or more elements that are combined together chemically

    • (H2O)

• MIXTURES

  • a mixture is a combination of pure substances

  • each substance remains in its original pure form

  • Homogeneous Mixtures

    • Solutions

      • Saltwater

      • Sugar dissolved in water

    • Alloys

      • Brass (Copper + Zinc)

      • Bronze (Copper + Tin)

  • Heterogeneous Mixtures

    • Suspensions

      • Sand in water

      • Oil and water

    • Colloids

      • Milk

      • Fog

Observing Physical Properties

• Physical properties

  • Color and luster - The light the substance reflects gives it color and luster (shine)

  • Conductivity - Conductivity is the ability of a substance to conduct electricity or heat. A substance that conducts electricity or heat is called a conductor. A substance with little or no conductivity is an insulator

  • Density- amount of mass in a given volume of a substance (d = m/v)

  • Ductility - any substance that can be stretched into a wire is ductile

  • Hardness - ability of a substance to resist being scratched

  • Malleability - A substance that can be pounded or rolled into sheets is said to be malleable.

• Physical Change

  • substance remains same chemically and may change state or form

    • most physical changes can be reversed

• Chemical properties

  • Combustibility is the ability of a substance to burn. In

    order to burn a substance requires Oxygen

  • Light sensitivity is a chemical property of that can cause

    new substances to form when light hits it.

  • Reacting with an acid is a chemical property where

    when acid is poured on a substance it produces a gas and

    bubbles.

The Periodic Table Organizes Elements by Patterns in Properties and Atomic Structure

• Evolving Models of the Atom

  • John Dalton (1766–1844)

    • Proposed that all matter is made of small, indivisible particles called atoms.

    • Suggested that atoms of an element are identical in size and mass.

    • Stated that atoms of different elements have different properties and can combine to form new substances.

  • J. J. Thomson (1856–1940)

    • Discovered that atoms are not the smallest particles and contain smaller particles within.

    • Proposed the "raisin bun" or "plum pudding" model of the atom, with a positively charged sphere and negative charges embedded in it.

  • Ernest Rutherford (1891–1937)

    • Discovered the atomic nucleus, a tiny, positively charged part containing most of the atom's mass.

  • Subatomic Particles

    • Atoms consist of protons (positively charged), neutrons (neutral), and electrons (negatively charged).

    • Protons and neutrons are located in the nucleus, while electrons orbit in energy levels around the nucleus.

  • Niels Bohr (1885–1962)

    • Developed a model with electrons in specific energy levels or shells around the nucleus.

• Subatomic Particles

  • Protons- Heavy positively charged found in the nucleus

  • Neutrons -are neutral particles that have the same mass as protons and are located in the nucleus

  • Electrons- Negatively charged particles with almost no mass. They circle the nucleus at different energy levels.

• The elements

  • Elements are pure substances that consist of atoms.

  • The periodic table consists of over 100 elements all of which have a certain spot on the table.

• Non-Metals

  • Found on the right side of the periodic table.

  • Generally non-conductors of electricity in solid form, and most are gases or solids at room temperature.

  • Non-metal solids are brittle and lack the luster of metals.

• Metalloids

  • Located near the middle-right of the periodic table.

  • Have properties of both metals and non-metals and are known as semiconductors.

  • Commonly used in electronics due to their semi-conductive properties.

    

• Ion Charge

  • Elements with atoms that can form similar ions are grouped together in the periodic table. Metals generally lose electrons and become positive ions.

  • Many non-metals can gain electrons and so become negative ions.

• Determining the number of neutrons

  • Subtract the atomic number (# of protons) from the Atomic mass (# of protons and neutrons)

    • Atomic mass – atomic number (A – Z = N)

    • Example: Iron

      • 55.85 – 26 = 30 neutrons

• Metals and Non-metals

  • Metals tend to lose electrons to form positive ions (cations).

  • Non-metals gain electrons to form negative ions (anions).

  • Electron arrangements in ions resemble those of noble gases.

• Ionic Compounds

  • This leaves the metal ion as a cation and the non-metal ion as a anion. The two oppositely charged ions are attracted to each other by a force called a ionic bond.

  • The smallest amount of substance that has the composition given by its chemical formula is the formula

• Ionic properties

  • Ionic compounds are solids at SATP. In their solid form they form solid ionic crystals. These are more commonly known as salts.

• The cross over rule

  • write the symbols, with the metal first (the element with the positive charge)

  • Write the Ionic charge above each symbol to indicate the stable ion that each element

  • Draw an arrow from the metals charge to the non-metal and an arrow from the non-metal charge to the metal. (Cross over the arrows)

  • Fill in the number of atoms from each element will have by following the arrows.

  • If need be reduce to lowest terms (in other words, if they are the same number, you don’t write those numbers down because you could divide the whole molecule by that number which would = 1)

• Molecular Compound

  • When non-metals combine, a pure substance called a molecular compound is formed. In molecular compounds, the atoms share electrons to form covalent bonds. The atoms bonded together are called molecules.