Matter, Bonds, and Lab Safety

Vocabulary

• Matter is anything with mass or volume.
• Particle Theory describes the understanding of what matter is made of.
• Qualitative refers to descriptive words.
• Quantitative uses numbers and specifications.
• Physical Property describes the substance in an unaltered state.
• Chemical Property refers to the potential or factors to undergo chemical change.
• A Molecule is two or more atoms of the same or different elements.
• A Compound contains at least two different atoms.
• Molecular compounds are substances formed by atoms held together through covalent bonds.
• A Covalent bond is a chemical bond where two or more atoms share electrons to become stable.
• An Ionic bond is a chemical bond where atoms transfer, creating oppositely charged ions.

Safety

• Globally Harmonized Symbols are used for safety.
• A gas cylinder indicates gases under high pressure in a container, such as oxygen tanks.
• A flame symbol indicates a fire hazard, such as ethanol.
• Fire hazards easily catch fire, especially near heat sources.

Particle Theory

• Matter has mass and volume and is made of particles.
• Matter exists as a solid, liquid, or gas.
• Particle Theory (PISAM)
  • Particles may be atoms or molecules and can only be seen with a specific microscope.
    • A single particle atom is not connected to another.
    • A molecule has at least two chemically bonded atoms.
  • Particles of the same pure matter are identical in all samples of that matter.
  • All particles have space between them; solid < liquid < gas.
  • All particles are somewhat attracted to each other; solid > liquid > gas.
  • All particles in matter are always in motion.
• States of Matter
  • Matter changes state due to energy.
  • With energy or decreased attraction, particles move farther apart.
  • Solid > liquid > gas

Classification of Matter

• Classification helps group objects based on similarities.
• Generally, matter is separated into two categories: pure substances and mixtures.
• Pure Substances
  • Elements: Matter composed of only one type of atom that can be found on the Periodic Table.
  • Compounds: Matter composed of only one type of molecule, with at least two different atoms.
• Mixtures
  • Mechanical Mixture: Consists of two or more compounds that are easily seen and typically easy to separate; heterogeneous.
  • Suspension: Consists of two or more compounds that are cloudy, can be separated through filtering or over time, and is either heterogeneous or homogenous.
  • Solution: Consists of two or more compounds that are completely transparent, does not spontaneously separate, and is homogenous.

History of the Atom

• Greek Philosophers
  • They discussed the smallest piece of matter 2500 years ago.
  • They called it "Atomos".
• Dalton
  • Used electrolysis separated hydrogen and oxygen.
  • Created what is now known as Dalton's Atomic Theory (ASIC) through experimentation.
    • All matter is made up of atoms
    • Atoms cannot be created, destroyed, or divided into smaller pieces
    • Atoms in all samples of the same pure matter are identical
    • Compounds are created when two or more atoms chemically bond together
• Thomson
  • The gas discharge tube experiment discovered negatively charged material.
  • The electron was the first subatomic particle discovered.
  • He named the particle "electrons".
  • Since atoms are neutrally charged, there must be positively charged material in the atom.
• Rutherford
  • The gold foil experiment saw most particles go through, but some bounced back.
  • Most of the atom is empty space with negatively charged particles.
  • The center was a small, dense, positively charged particle
  • The center was the nucleus.
  • Rutherford later named specific positive particles "protons".
• Bohr
  • Electrons are in very specific patterns on energy levels.
  • Examined specific wavelengths of light emitted by each atom.
• Chadwick
  • Demonstrated neutral particles in the atom, called neutrons

Isotopes

• Isotopes are atoms of the same element with a different number of neutrons.
• Protons and electrons are the same.
• The atomic mass of each element will be different.
• Isotopes have the same chemical property but may have different physical properties.
• Isotopes are indicated by writing the symbol dash atomic mass like carbon-14 or C-14.

Representing the Atom

• Proton:
  • Mass: 1
  • Charge: +
  • Location: Nucleus
• Neutron:
  • Mass: 1
  • Charge: 0
  • Location: Nucleus
• Electron:
  • Mass: 1/1836
  • Charge: -
  • Location: Energy levels
• Elements are organized by the number of protons, called the atomic number.
• Atomic mass is protons + neutrons.
• In a neutral atom, protons = electrons.
• Standard Notation (X)
  • A = atomic mass
  • Z = atomic number (# of protons)
  • X = element symbol

Changes

• Physical Changes
  • Change in form or appearance of a substance without altering its chemical composition.
  • No new substances are created.
  • They are reversible.
  • Melting ice/dissolving sugar in water are examples.
• Chemical Changes
  • Changes into a new substance.
  • Indicator.
    • Not reversible
    • Change in energy
      • Exothermic: Energy is released, feels warm.
      • Endothermic: Energy is absorbed, feels cold.
    • Formation of a gas -Fizzy or bubbling.
    • Formation of a precipitate -Solids are formed after mixing two liquids.
    • Change in color -Typically sudden and drastically different, but does not always apply.
• Gas Tests
  • Oxygen test uses a glowing splint; reignition of a splint indicates oxygen= brighter glow.
  • Hydrogen test uses a flaming splint, resulting in a "squeaky pop."
  • Carbon dioxide test uses a flaming splint that puts out the flame, lime water test milky, cloudy precipitate.
  • Water vapor test uses Cobalt Chlorine Paper, which turns from blue to pink.

Chemical Compounds

• Dalton theorized that compounds are formed when atoms combine in specific proportions or ratios.
• Early scientists noted that the properties of atoms in a chemical reaction differed from the properties of the final products.
• Sodium metal and chlorine gas are individually poisonous; reacting them creates sodium chloride, which is relatively safe.

Molecular Compounds

• Molecular compounds are formed when electrons are shared between a non-metal and a non-metal atom.
• Ionic compounds do not involve ions, and no charges are involved.
• Each atom still receives a complete octet, therefore stable.
• Covalent bonds are strong and difficult to break.
• The bonds between molecules are much weaker.
• Properties:
  • State at room temperature: Molecular compounds have a much lower melting temperature than ionic compounds can be any state depending on how attracted the particles are to each other and are generally less organized than ionic compounds.
  • Solubility in water: Molecular compounds generally dissolve poorly in water. A can of pop has carbon dioxide escaping from the liquid.
  • Conductivity: Molecular compounds don't conduct heat or electricity well and are good insulators.

Ionic Compounds

• Ionic compounds are typically formed between a metal and a non-metal.
• Elements must become ions to make an ionic bond.
  • Elements gain or lose electrons to become a stable ion which has a complete octet in the valence energy level.
    • Metals lose electrons, resulting in a positive charge creating cations.
    • Non-metals gain electrons, resulting in a negative charge creating anions.
• Electrostatic bonds are made because positive and negative charges are attracted to each other.
• Properties:
  • State at room temperature: ionic compounds are solids and combine at the atomic level in the shape of a lattice structure and have very high melting temperatures to break the bonds.
  • Solubility in water: ionic compounds dissolve readily; ions are pulled apart and float around the solution.
  • Conductivity: solid ionic compounds don't conduct, but when dissolved in water, its ions float around the solution to create an electrolyte.

Nomenclature

• Nomenclature comes from Latin words "nomen" (name) and "clatura" (calling/summoning).
• Every chemical has a chemical name and formula.
  • For example chemical name is sodium chloride.
  • For example chemical formula is NaCl.
• Ionic Naming
  • Name the metal element first.
  • Name the non-metal element second and change the ending to "ide."
  • The number of elements involved doesn't change the name.
• Molecular Naming -Prefices for naming: - 1-mono - 2-bi - 3-tri - 4-tetra - 5-penta - 6-hexa - 7-hept - 8-octa - 9-nona - 10-deca
  • Name the first element with the prefix.
    • Don't use "mono" if there is only one.
  • Name the second element using an "ide" ending, use a prefix.

Periodic Table Patterns

• Group 1 - Alkali Metals:
  • high reactivity
  • soft, shiny, silver
• Group 2 - Alkaline Earth Metals:
  • less reactive, shiny, slightly soft
• Group 7 - Halogens:
  • highly reactive, existing in all states
• Group 8 - Noble Gases:
  • most stable, produce light when electricity travels through.
• Vertical Columns
  • Groups or families share the same amount of valence electrons.
  • The number of valence electrons determines how reactive an element is.
  • Noble gases are the most stable or least reactive/
  • Chemicals react, they try to achieve a complete octet.
  • Closer to complete octet = more reactive.
• Periods or Horizontal Rows
  • Same period/row = same number of energy levels
  • More energy levels = larger in size.

Periodic Table

• Arranged independently by Lotar Meyer (German) and Dimitri Mendeleev (Russian) before subatomic particles were discovered.
• Dimitri Mendeleev received most of the credit because the P.T. allowed the placement of elements which had not been discovered at the time and elements were arranged by their chemical property.
• Valence
  • Now: electrons on the outermost energy level.
  • Before: how many other elements it could bond with.
• Diagrams
  • Bohr Rutherford Diagrams
    • Symbol, protons, neutrons
    • 1 energy level: 2 electrons
    • 2nd and more: 8 electrons (N,E,S,W)
  • Lewis Diagrams
    • Chemical formula
    • Dots represent valence (N,E,S,W)
• Category Properties:
  • Metals
    • Lustre- Shiny + metallic
    • State- Solid at room temp
    • Conductivity- good conductors
    • Malleable- Very
    • Ductile- yes
  • Metalloids
    • Lustre- can have either
    • State- Solid at room temp
    • Conductivity- can conduct, not as good as metals
    • Malleable- depends
    • Ductile- no
  • Non Metals
    • Lustre- generally dull
    • State- gas or solid (bromine =L)
    • Conductivity- poor conductors
    • Malleable- no
    • Ductile- no