Atomic Composition & Structures
A large crystal of quartz made of repeating subunits of atoms bonded together into a continuous lattice.
What is an extended structure?
Seeing gas bubbles form or measuring a decrease in temperature when mixing two substances are key evidence of this process.
What is a chemical reaction?
Scientific law stating that atoms are rearranged in a chemical reaction, but total mass and total number of atoms never change.
What is the Law of Conservation of Mass (or Matter)?
In the molecule CO2, the subscript "2" indicates that there are two atoms of this element.
What is oxygen?
The starting substances located on the left side of a chemical equation arrow.
What are reactants?
Breaking apart a molecule of CO2 into carbon and oxygen destroys its chemical bonded structure, meaning it is no longer this gas.
What is carbon dioxide?
Mixing vinegar and baking soda causes a chemical reaction because it produces temperature changes and these.
What are gas bubbles?
If 58.5 grams of reactants (Na + Cl) react completely in a closed system, this is the exact mass of the sodium chloride (NaCl) product.
What is 58.5 grams?
The total number of atoms present in a single molecule of methane (CH4.)
What is 5 atoms (1 carbon and 4 hydrogen)?
The new chemical substances formed during a reaction, located on the right side of the chemical equation arrow.
What are products?
A molecule composed of 1 nitrogen atom and 3 hydrogen atoms (NH3).
What is ammonia?
When two substances combine, gas forms, and the container gets colder. What sign of a chemical reaction is this?
What is temperature change?
In the combustion reaction CH4 + 2 O2 ----> CO2 + 2 H2O, this is the total count of oxygen atoms on both the reactant side and the product side.
What is 4 oxygen atoms?
The total number of hydrogen atoms shown on the product side of the balanced equation CH4 + 2 O2--->CO2 + 2 H2O.
What is 4 hydrogen atoms?
In the reaction Na + Cl ---->NaCl, the single product that forms is known by this chemical formula.
What is NaCl (or Sodium Chloride / Table Salt)?
This single molecule consists of exactly two hydrogen atoms bonded to one oxygen atom.
What is a water molecule (H2O)?
When two clear liquids are combined in a beaker and a solid substance forms at the bottom, this specific type of solid evidence proves a chemical reaction occurred.
What is a precipitate?
A system that traps all reactants and products so that gas cannot escape, allowing students to verify that mass before equals mass after.
What is a closed system?
A student draws a model of water with 2 oxygen atoms and 2 hydrogen atoms (H2O2.) To correct it to a standard water molecule (H2O), the student must take this step.
What is removing one oxygen atom?
During a chemical reaction, bonds between atoms in the reactants break and reform into products, meaning the atoms are neither created nor destroyed, but simply undergo this process.
What is rearrangement (or being rearranged)?
If you chip a piece off a quartz crystal lattice, it remains quartz, but if you break apart a single molecule of carbon dioxide gas, it is no longer carbon dioxide. This is because extended structures are made of repeating subunits, whereas simple molecules rely on this to maintain their identity.
What is a specific, bonded chemical structure (or set ratio of bonded atoms)?
A student notices that rust forms on an iron nail left outside, accompanied by an unexpected, permanent color change and a change in odor. This type of transformation provides evidence of a chemical reaction because it forms an entirely new substance with these different properties.
What is a chemical change (or chemical property change)?
A student claims matter was destroyed because a gas was produced and the open beaker weighs less after the reaction. Explain why this student is incorrect.
What is "The atoms didn't disappear—the gas escaped into the air because it was an open system; if measured in a closed container, the mass before and after would be identical"?
A student models two separate water molecules using chemical formulas. The correct way to write this using a coefficient in front of the formula is this expression.
What is 2 H2O?
2In the photosynthesis equation where carbon dioxide and water produce glucose and oxygen (6 CO2 + 6 H2O---->C6H12O6 + 6 O2), these two chemical compounds act as the reactants.
What are carbon dioxide (CO2) and water (H2O)?