What is matter defined as?
Anything that has mass and takes up space
Matter is divided into Pure Substances and Mixtures.
What are the two main categories of matter?
- Pure Substances
- Mixtures
Pure substances contain only one type of particle, while mixtures are physically combined substances.
Define pure substance.
Contains only one type of particle and has a fixed composition
Examples include elements and compounds.
What are the two types of pure substances?
- Elements
- Compounds
Elements are made of one type of atom, while compounds are made of two or more elements chemically combined.
Give an example of an element.
Oxygen (O)
Elements cannot be broken down chemically.
Give an example of a compound.
Water (H₂O)
Compounds can be broken down chemically.
What is a mixture?
When substances are physically combined
Mixtures can be separated physically.
What are the two types of mixtures?
- Homogeneous Mixture
- Heterogeneous Mixture
Homogeneous mixtures look uniform, while heterogeneous mixtures have different visible parts.
What is a homogeneous mixture?
Looks uniform and has only one visible phase
Also called a solution; examples include salt water and air.
What is a heterogeneous mixture?
Different parts visible and not uniform
Examples include salad and sand in water.
Define physical property.
Can be observed without changing the substance
Examples include color, density, and boiling point.
Give an example of a physical property.
Density
Density is a physical property that helps identify substances.
Define chemical property.
Describes how a substance reacts to form a new substance
Examples include flammability and reactivity.
Give an example of a chemical property.
Flammability
It describes how a substance can catch fire.
What is density?
How much mass is packed into a certain volume
It helps identify substances.
What is the density formula?
Density = Mass / Volume
Rearranged formulas include Mass = Density × Volume and Volume = Mass / Density.
What are common density units?
- g/cm³
- g/mL
- kg/m³
These units are used to express density.
What is a physical change?
Changes the form or state, but not the substance
Examples include melting ice and boiling water.
What is a chemical change?
Produces new substances
Signs include color change and gas produced.
What are the periods in the periodic table?
Horizontal rows indicating the number of electron shells
Each period corresponds to a different energy level.
What are the groups (families) in the periodic table?
Vertical columns with similar chemical properties
Elements in the same group have the same number of valence electrons.
What does atomic size do across the periodic table?
Increases down and decreases across
This trend is important for understanding element behavior.
Who proposed the first scientific atomic theory?
John Dalton
He described atoms as solid spheres.
What does standard atomic notation include?
Z, A, X
Where X is the element symbol, A is the mass number, and Z is the atomic number.
