Unit 2: PRACTICE Test - Density, Matter, Atoms, Periodic Table

Front

What is a pure substance?

Back

Matter made of only one kind of particle. Cannot be separated by physical means. Includes Elements and some Compounds. Ex: Gold (Au), Iron (Fe), Water (H₂O)

Front

What is an element?

Back

Pure substance made of ONLY ONE TYPE of atom. Formula has 1 capital letter. Ex: O₂, C, Na

Front

What is a compound?

Back

Substance made of 2+ DIFFERENT elements that are CHEMICALLY COMBINED. Formula will have 2+ capital letters. Ex: H₂O, NaCl, CO₂

Front

What is a Molecule?

Back

2+ atoms bonded together (can be SAME OR DIFFERENT elements). Smallest unit of a compound to retain its properties. All compounds are molecules, but not all molecules are compounds. Ex: O₂ (molecule but NOT compound), H₂O (both molecule + compound)

Front

What is a Mixture?

Back

2+ substances PHYSICALLY COMBINED (NOT chemically). Can be separated physically. Ex: Salty water, Air, Trail Mix

Front

What is a Homogeneous mixture?

Back

Looks the SAME throughout (uniform). Ex: Salt dissolved in water, Air, Lemonade, Kool-Aid

Front

What is a Heterogeneous mixture?

Back

Visibly DIFFERENT parts (not uniform). Ex: Salad, Trail mix, Oil & water

Front

What is the density of water, and how does it determine if an object sinks or floats?

Back

The density of water is 1 g/cm³. If an object's density is greater than 1 g/cm³, it will sink. If an object's density is less than 1 g/cm³, it will float.

Front

How to calculate VOLUME if you have length, width, height?

Back

Length x width x height. Ex: a block 3cmx3cmx3cm is 9cm³

Front

How do you determine the DENSITY?

Back

Density = Mass/Volume. Remember units: Mass is generally in grams (g); Volume is cm³ or mL; Density is g/cm³ or mL