Question

part 1: read the following information on elements, compounds and mixtures. circle or fill in the correct term for each blank where necessary.
elements:

• a pure substance containing only one kind of atom
• an element is always uniform all the way through (homogeneous).
• an element can / cannot be separated into simpler materials (except during nuclear reactions).
• over 100 existing elements are listed and classified on the periodic table

compounds:

• a pure substance containing two or more kinds of elements
• the atoms are chemically/physically combined in some way. often times (but not always) they come together to form groups of atoms called molecules.
• a compound is always homogeneous (uniform).
• compounds can / cannot be separated by physical means. separating a compound requires a chemical reaction.
• the properties of a compound are usually different than the properties of the elements it contains.

mixtures:

• two or more elements or compounds not chemically combined.
• no reaction between substances.
• mixtures can be uniform (called homogenous) and are known as solutions.
• mixtures can also be non - uniform (called heterogenous).
• mixtures can be separated into their components by chemical or physical means.
• the properties of a mixture are similar to the properties of its components.

part 2: classify each of the following as elements (e), compounds (c) or mixtures (m). write the letter x if it is none of these.
e diamond (c) c sugar (c₆h₁₂o₆) milk e iron (fe)
air c sulfuric acid (h₂so₄) gasoline e electricity
e krypton (k) e bismuth (bi) e uranium (u) m popcorn
c water (h₂o) c alcohol (ch₃oh) m pail of garbage a dog
c ammonia (nh₃) c salt (nacl) energy e gold (au)
wood bronze x ink m pizza
c dry ice (co₂) c baking soda (nahco₃) e titanium (ti) concrete

Explanation:

• Elements: A pure substance with only one kind of atom. Examples include Diamond (C), Krypton (K), Bismuth (Bi), Uranium (U), Gold (Au), Titanium (Ti), Iron (Fe). They are uniform (homogeneous), can't be separated into simpler materials (except nuclear reactions), and over 100 are on the periodic table.
• Compounds: A pure substance with two or more kinds of elements. Atoms are chemically combined. Examples: Sugar ($C_6H_{12}O_6$), Sulfuric Acid ($H_2SO_4$), Water ($H_2O$), Alcohol ($CH_3OH$), Salt ($NaCl$), Ammonia ($NH_3$), Dry Ice ($CO_2$), Baking Soda ($NaHCO_3$). They are homogeneous, can't be separated by physical means, and properties differ from component elements.
• Mixtures: Two or more elements or compounds not chemically combined. Can be uniform (homogeneous - solutions) or non - uniform (heterogeneous). Examples: Air, Milk, Gasoline, Popcorn, Pail of Garbage, Wood, Bronze, Pizza, Concrete. Can be separated by chemical/physical means, properties similar to components.
• Others (X): Electricity, Energy, Ink, A dog. Electricity and Energy are not substances (matter). Ink is a complex mixture but not in the simple E/C/M categories here (more of a commercial product mixture with dyes etc. not just elements/compounds simply mixed). A dog is a living organism, not a chemical substance in terms of E/C/M classification.

Answer:

• Diamond (C): E
• Sugar ($C_6H_{12}O_6$): C
• Milk: M
• Iron (Fe): E
• Air: M
• Sulfuric Acid ($H_2SO_4$): C
• Gasoline: M
• Electricity: X
• Krypton (K): E
• Bismuth (Bi): E
• Uranium (U): E
• Popcorn: M
• Water ($H_2O$): C
• Alcohol ($CH_3OH$): C
• Pail of Garbage: M
• A dog: X
• Ammonia ($NH_3$): C
• Salt ($NaCl$): C
• Energy: X
• Gold (Au): E
• Wood: M
• Bronze: M
• Ink: X
• Pizza: M
• Dry Ice ($CO_2$): C
• Baking Soda ($NaHCO_3$): C
• Titanium (Ti): E
• Concrete: M