Unit 1: Matter & Density Flashcards
(23 cards)
In your own words, define chemical change
The reaction creates a new compound entirely.
Ex. Rust on a car
List three different physical and chemical changes and one physical and chemical change.
Physical change: ice, water (liquid), stem
Chemical change: burning, rusting, decomposing
Both: baking cookies, digestion
Elements
Made of one kind of atom, distinguished by atomic number, which corresponds to the number of protons in the nucleus.
Compounds/molecule/formula unit
Group of atoms that are bonded together. These are made up of different atoms
Pure Substances
Only one type of atom or molecule, no impurities
Mixture
Two or more substances that are mixed together pm nut not bonded
Heterogenous Mixture
Mixtures that do no appear to be the same throughout ( different )
Homogeneous Mixtures
Mixtures that appear to be the same thought ( same )
Provide four evidences of a chemical change
1) change in heat
2) CHANGE in color
3) gas formed
4) precipitate (ppt) formed ➡️ forms a solid
In your own words, define physical property
Come back to
In your own words, define chemical property
A quality of substance that can be measured or noticeable throughout a chemical reaction.
Significant Digits (figures)
The number of digits that are believed to be accurate, including one estimated digit
➡️telling us how precise a measurement is and should be carefully considered
Why do we use significant digits?
To help us report our data, and show how accurate our measurements/reports are.
➡️along with increased accuracy, they also increase the rigor of our findings.
Exact Numbers
Counting numbers ➡️ number of markers (no decimals)
Definition number
‼️have infinite significant figures‼️
Significant figures: Zeros 0⃣
Leading➡️ NEVER SIGNIFICANT ‼️
Trailing➡️ only significant if there is a DECIMAL ➗
Trapped➡️ ALWAYS significant 🔝🚯 😍
When adding or subtracting significant figures, your answers should always depend on what key principle?
The same number of decimals ➗ as the number of least amount of ❌💸 decimals ➗.
DONT FORGET TO ROUND
When multiplying or dividing significant figures, you should always do what to determine the number of significant figures in your answer?
Look to see what is the least amount of significant figures and make that the same number of significant figures in your answer. In other words, your answer should have the same number of significant figures as the number with the least amounts ❌💸 of significant figures.
What are two things significant figures require?
Rounding and on occasion scientific notation.
Why the metric system?
1) simpler ➡️ based on tens
2) consistency ➡️ all countries except for three use the metric system. It makes talking about science a lost easier when everyone is talking in the same language.
Recite the factor label method
1) write down the given quantity and put it over 1
2) determine what conversion factor you will use to turn the given label into the needed label
3) multiply the given quantities by the appropriate conversation factors to eliminate units you don’t want & leave the units you do.
4) round your answer to significant figures and write your units
Explain what density is.
A ration of an objects mass to volume.
Usually measure in grams and milliliters
What is the equation for density?
D=m/v
‼️ remember, density cuts your heart in half D + ❤️ = 💔 ❌❌❌ ‼️
In your own words, define physical change
A substance is transformed, but the chemical composition is not changed.
Ex. An egg➡️ hard boiled egg
