Elements
This is a pure substance made of only one type of atom.
What is an element.
This type of pure substance is formed when two or more elements are chemically bonded together.
What is a compound?
This type of mixture has a composition that is NOT uniform throughout, like trail mix or sand and water.
What is a heterogeneous mixture?
This type of reaction releases heat energy to the surroundings, making the area feel warmer.
What is an exothermic reaction?
: According to the Law of Conservation of Mass, mass cannot be created or __________ during a chemical reaction.
What is destroyed?
This element has the symbol O and is essential for breathing and combustion.
What is Oxygen.
This compound has the formula H₂O.
What is water?
This type of mixture has a uniform composition throughout, like saltwater or air.
What is a homogeneous mixture?
This type of reaction absorbs heat energy from the surroundings, making the area feel cooler.
What is an endothermic reaction?
In a chemical reaction, the total mass of the reactants will always equal the total mass of the __________.
What are products?
This element with the symbol C is found in all living things and forms diamonds and graphite
What is Carbon.
This compound made of sodium and chlorine (NaCl).
What is sodium chloride or table salt?
Classify this mixture: A bowl of cereal with milk where you can see the individual pieces.
What is a heterogeneous mixture?
An instant cold pack used for injuries gets cold when activated. Is this endothermic or exothermic? And Why?
What is endothermic?
Look at this equation: 2H₂ + O₂ → 2H₂O. Is this equation balanced, showing conservation of mass?
What is yes (4 hydrogen atoms and 2 oxygen atoms on each side)?
Explain why gold (Au) is considered an element rather than a compound.
What is "it only contains one type of atom" or "it cannot be broken down into simpler substances"
This compound with formula CO₂ is?
What is carbon dioxide?
Classify this mixture: Sugar dissolved completely in hot tea so you cannot see the sugar crystals.
What is a homogeneous mixture?
Burning wood in a campfire releases heat and light. Is this endothermic or exothermic? And why?
What is exothermic?
A student burns a piece of paper in an open container and notices the ash weighs less than the original paper. Does this violate the Law of Conservation of Mass? Explain.
What is "No, because gases (smoke and carbon dioxide) escaped into the air, so mass was not lost, just changed form"?
This element with symbol Fe is?
What is iron?
Explain why water (H₂O) is a compound and not a mixture of hydrogen and oxygen.
What is "the hydrogen and oxygen are chemically bonded" or "it has different properties than hydrogen and oxygen alone"
A student mixes sand and iron filings in a container. Explain why this is a heterogeneous mixture and not a compound.
What is "you can see the different components/it's not uniform throughout" AND "the substances are not chemically bonded"?
A student observes that when chemical A and chemical B are mixed in a test tube, the test tube becomes very hot to touch. Explain what type of reaction this is and what happened to the energy.
What is "exothermic" and "energy was released from the reaction to the surroundings"?
In the equation CH₄ + O₂ → CO₂ + 2H₂O, does this show conservation of mass? Count the atoms on each side to support your answer.
What is "No, it is not balanced" (1 C, 4 H, 2 O on left; 1 C, 4 H, 4 O on right - oxygen is not equal)?