Chemistry (The Atomic model and structure) notes and practice questions with answer key

Matter & Chemistry Basics
Important Information

What is Chemistry?
●​ Chemistry is the study of matter and how it changes.​


What is Matter?
●​ Matter is anything that has mass and volume (takes up space).​

●​ Matter is classified by its composition:​

○​ Types of particles​

○​ Arrangement of particles​

○​ Attractions/attachments between particles​



Pure Substances vs Mixtures
Pure Substances
●​ Composition does not change​

●​ Made of one type of atom or molecule​

, ●​ All samples have identical properties​


Elements

●​ Cannot be broken down by chemical reactions​

●​ Made of one type of atom​

●​ Basic building blocks of matter​


Compounds

●​ Can be broken down chemically​

●​ Made of two or more different atoms​

●​ All molecules are identical​

●​ Most natural substances are compounds​


Mixtures
●​ Composition can vary​

●​ Physically combined substances​

●​ Can be separated without chemical changes​


Homogeneous Mixtures

, ●​ Uniform throughout​

●​ Looks the same everywhere​

●​ Example: gasoline​


Heterogeneous Mixtures

●​ Uneven composition​

●​ Different regions visible​

●​ Example: oil and water​



Chemical Formulas & Identification
●​ Chemical formulas show:​

○​ Elements present​

○​ Number of each atom​

●​ Subscripts = number of atoms​

●​ Coefficients = number of molecules​


Naming Rules