3. Pure Substance Compound Element
—matter that has a constant composition and distinct properties; differ from one another in composition
Compound
Element
Substance composed of atoms from two or more elements chemically bonded in fixed proportions
Differ by type of force (chemical bond) holding the atoms together
Has properties different than its components
Can be separated into components by only chemical means (electricity & heat)
Substance that cannot be separated into simpler substances
3 categories: monatomic, diatomic, or polyatomic
*Atom—smallest particle of an element that retains all properties of the element

4. Chemical Formula
Express the composition of substances in terms of their chemical symbols
Subscripts denote the number of atoms
Subscripts outside parentheses get multiplied in
Coefficients are multipliers

5. Compound Metallic Ionic Molecular
Composed of cations held together by metallic bonds (sea of electrons)
Composed of ions held together by ionic bonds
Composed of molecules held together by intermolecular forces
Molecules held together by covalent bonds
*Molecule—two or more atoms covalently bonded as a discrete unit

6. urea Chalcopyrite gold ingots liquid nitrogen silicon crystals
aluminum
Elemental sulfur
quartz
dry ice – carbon dioxide
lithium fluoride
Copper
urea

9. Allotrope
—two or more different forms in which an element can exist; differ in physical and chemical properties

10. Mixture Heterogeneous Homogeneous
—matter that is made from a combination of two or more pure substances where each pure substance retains its individual identity; do not have fixed proportions; created or separated by physical means
Heterogeneous
Homogeneous
individual substances remain visually distinct
Visibly indistinguishable parts (uniform appearance)
Mixed at the molecular level
Also called a solution

12. Alloy Substitutional Interstitial
—combination of metals or metal and another element; has properties superior to its constituents
Substitutional
Interstitial
Atoms of the added component(s) take up spaces that are normally occupied by atoms of the host element
Similar in size
Atoms of the added component(s) occupy spaces in between atoms of the host metal
Discrepancy between atom sizes