General Chemistry Essay

Submitted By ysquared168
Words: 1149
Pages: 5

1 Chemical Foundations

1. Chemistry - study of composition, structure, + prop. of matter, processes that matter undergoes, + E in processes
2. Chemical - any subs. with a def. composition; matter is composed of dif. types of atoms; 1 subs. changes to another by reorganizing the way atoms are bonded

Chem. reaction - one or more subs. are converted into different subs.; atoms are re-organized
3. Law of Conservation of matter/mass/energy – matter/mass is neither created nor destroyed in chem. rxn
1. Signs of chem. reactions:

1. Gas evolution (ex. fizzing)
1. Heat evolution
2. Color change
3. Light evolution
4. Solid formation

Matter - anything that has mass + has volume; composed of atoms + molecules

4. Volume - amt of space occupied; 1 mL = 1 cm3
5. Mass - amt of matter in object; measure of resistance of object to change in state of motion
1. F = ma
6. Weight – force that gravity exerts on an object; W = mg (mass ≠ weight)
7. Density =
8. Inertia – property of mass to resist change of position or motion
9. Physical states of matter – can be changed by addition/subtraction of heat energy
1. Gas - neither def. vol. nor def. shape
1. Liquid - def. vol. but an indef. shape
2. Solid - def. vol. + def. shape
3. Plasma - high-T; atoms lose e-

2. Composition
1. Atom - smallest unit of an element that maintains prop. of that element; 109 kinds
1. Diatomic atoms – H, F, O, N, Cl, At, Br, I (HONCl At BrIF)
2. Element - pure subs. of only 1 kind of atom; all atoms have same atomic # (not nec. mass #); can’t be sep. into simpler substances by chemical means
2. Substance – a kind of matter that can’t be separated into other types of matter by a physical process
3. Pure/distinct subs. - subs. that has a fixed composition + all samples have same prop. + composition; ex. H2O
2. Compound – ≥ 2 kinds atoms chemically bonded; constant composition (homogeneous); always has same relative # + types of atoms
1. Can be broken into elements thru chem. methods (ex. electrolysis of water)
2. All parts react same
1. Properties of compound are dif. from properties of individual elements
2. ^Molecule – smallest unit of compound; 2 or more atoms that have a fixed proportion according to mass; composed of atoms held together by covalent bond
1. Types – most (exc. metallic) are defined by electronegativity (willingness of atom to hold on to electrons)
1. Ionic – simple ionic, polyatomic
2. Partially ionic – ex. acid/base
3. Non-ionic (covalent)
4. Metallic
3. Mixture - blend of two or more kinds of matter; constituents retain prop. + identity; can become pure subs. by phys. methods; has variable composition
4. Heterogeneous – non-uniform composition throughout; sep. by filtration (used when mixture has solid + liquid), density dif., magnetic prop.
5. Homogeneous - uniform composition throughout
1. Solution – a homogenous mixture; can be sep. by…
2. Crystallization; distillation - diff. in volatility – how readily subs. become gases
3. Chromatography - sys has 2 phases, mobile (liquid/gas) + stationary (solid); components have dif. affinities for 2 phases + move thru sys at dif. rates (high affinity for mobile moves faster)
4. ex. paper chromatography – strip of porous paper for stationary phase; drop of mixture placed on paper + dipped into liquid + travels up paper
10. Classifications

1. By chem. constitution – element, compound, mixture
2. By phys. state – solid, liquid, gas

11. Prop. Types
1. Phys. prop. - can be observed or measured with senses
1. ex. Color, shape, amount, change of phase, density, temperature
2. Phys. change – change in state of matter but not in chem. composition (doesn’t alter i.d.); ex. boiling, freezing
2. Chem. prop. - ability of a subs. to undergo a change to transform into dif. substance
1. ex. Rusting, burning, with air, with water, ease of decomposing
2. Chem. change/rxn – subs. become new subs. with dif. prop. + composition (alters i.d.)
12. Prop.…