Elements, Compounds, and Mixtures Quiz

Elements, Compounds, and Mixtures

• Element: A substance that cannot be broken down into simpler substances by chemical means. It's made of only one type of atom.
• Compound: A substance made of two or more different types of atoms chemically bonded in a fixed ratio.
• Mixture: A combination of two or more substances that are physically combined but not chemically bonded.

Particle Diagrams

• Elements: A single type of atom.
• Compounds: Multiple types of atoms bonded together in a specific arrangement.
• Mixtures: Multiple types of atoms or molecules that are not chemically bonded, mixed together.

Metals and Non-metals (Periodic Table)

• Metal Identification: Use the periodic table to determine if an element is a metal or non-metal. Most elements on the left side of the periodic table are metals; non-metals are on the right.
• Metal Properties:
  • Solid state (except mercury)
  • Shiny/lustrous appearance
  • Good conductors of heat and electricity
  • Malleable (can be hammered into shapes)
  • High density
  • High melting points
• Non-metal Properties:
  • Can be solid, liquid, or gas
  • Dull appearance
  • Poor conductors of heat and electricity
  • Brittle (break easily)
  • Low density
  • Low melting points

Identifying Metals/Non-metals

• Electrical Conductivity Test: Metals conduct electricity; non-metals do not.
• Appearance Test: Metals are shiny, non-metals are dull.
• Malleability Test: Metals can be bent or flattened; non-metals break.

Reactions with Oxygen

• Magnesium (Mg): Burns with a bright white flame, forming magnesium oxide (MgO).
  • Reaction: 2Mg + O₂ → 2MgO
• Calcium (Ca): Burns with an orange-red flame, forming calcium oxide (CaO).
  • Reaction: 2Ca + O₂ → 2CaO
• Carbon (C): Burns with a yellow-orange flame, forming carbon dioxide (CO₂) with enough oxygen. If oxygen is limited forms carbon monoxide (CO).
  • Complete combustion: C + O₂ → CO₂
  • Incomplete combustion: 2C + O₂ → 2CO

Reactions of Metal Oxides with Water

• Reactive metal oxides dissolve in water to form alkaline solutions (metal hydroxides).
• Example 1: Sodium oxide + Water → Sodium hydroxide: Na₂O + H₂O → 2NaOH
• Example 2: Calcium oxide + Water → Calcium hydroxide: CaO + H₂O → Ca(OH)₂

Metal Oxide Characteristics

• Metal Oxides: Usually solid, high melting points, may dissolve in water to be alkaline.
• Non-metal Oxides: Often gases or low-melting solids, may dissolve in water to be acidic.

Reactions of Metals with Water

• Metal + water → metal hydroxide + hydrogen
• Metal oxide + water → metal hydroxide
• Metal + oxygen → metal oxide
• Non-metal oxide + water → acid
• Metal + acid → salt + hydrogen gas

Reactions of Li, Na, and K with Water

• Lithium (Li): Reacts steadily, floats on water.
• Sodium (Na): More vigorous than Li, melts, moves on the water surface.
• Potassium (K): Extremely vigorous, ignites spontaneously, produces a lilac flame.

Metal Reactivity and the Periodic Table

• Reactivity Order (most to least reactive): Potassium > Sodium > Calcium > Magnesium > Aluminum > Zinc > Iron > Copper > Silver > Gold.

Combining Powers (Valencies)

• Group 1: +1
• Group 2: +2
• Transition metals (vary)
• Group 6: -2
• Group 7: -1
• Group 5: -3

Formulae of Compounds

• Find valencies of each element.
• Balance the valencies to make the total charge zero.
• Write the formula with subscripts to show the ratio.

Displacement Reactions

• More reactive element displaces a less reactive one from its compound.
• Use reactivity series to predict reactions.
• Identify the more reactive metal and the less reactive metal.

Observations During Displacement Reactions

• Color change
• Formation of precipitate
• Metal deposition
• Gas evolution
• Temperature change
• Odor change

Metal Extraction Methods

• Iron: Reduction with carbon in a blast furnace.
• Aluminum: Electrolysis.
• Copper, Zinc, Lead: Smelting or other methods involving carbon reduction.
• Silver/Gold: Found in native form or extracted using cyanide leaching.

Electrolysis Products

• Cathode: Positive ions (cations) are attracted. Will form metal or hydrogen gas.
• Anode: Negative ions (anions) are attracted. Will form non-metal compounds such as oxygen gas or halogen gases.

Predicting Metal Extraction Methods

• Highly reactive metals: Electrolysis
• Moderately reactive metals: Reduction with carbon
• Less reactive metals: Heating or found in native form

Electroplating

• Electrolysis used to coat an object with metal.

Variables in Experiments

• Independent Variable: The variable you change.
• Dependent Variable: The variable you measure.
• Controlled Variable: The factors kept the same.

Graphs

• Line Graphs: Plot data points, connect them with a line, label axes.
• Bar Charts: Bars represent data categories. Label axes, spacing between the categories.

Test your understanding of key concepts in chemistry related to elements, compounds, and mixtures. This quiz covers definitions, particle diagrams, and identification of metals and non-metals using the periodic table. Challenge yourself to differentiate between these fundamental chemical concepts!