Chemistry-Exam

Homogenous vs heterogenous

Heterogeneous: two or more easily distinguishable phases

Homogenous: one visible phase, hard to distinguish it's parts

Element vs compound

Element: pure substance; can't be broken down into simpler chemicals

Compound: pure substance; two or more elements; chemically joined

How shiny something is

Lustre

Substance that allows currents to pass through it

Conductivity

Mass of something per volume

Density

How well something can be stretched into wires

Ductility

Ability to scratch or be scratched by another object

Hardness

How well an object can be hammered into thin sheets or molded

Malleability

How easily liquid flows

Viscosity

Evidence of Chemical Change

1. New unexpected colour

2. Energy change (heat/light is produced/absorbed)

3. Gas produced (bubbles formed not from heat)

4. Precipitate (solid created from mixing 2 solutions)

5. Change is difficult to remove

Experimental test for determining the prescence of 1. Oxygen 2. Hydrogen 3. Carbon dioxide

Oxygen test: Put a glowing wooden stick inside the tube! stick relights into a flame.

Hydrogen test: lit match or stick at the tube opening; makes a loud squeaky "pop" sound.

Carbon dioxide: Pour gas into limewater and shake; clear liquid turns milky white.

Density formula

D = m*v

M = v*d

V = m/d

Element names for Al, Mg, N, B

Aluminum (Al), Magnesium (Mg), Nitrogen (N), and Boron (B).

Element Symbol: sodium, fluorine, hydrogen, beryllium

Sodium: Na

Fluorine: F

Hydrogen: H

Beryllium: Be

Mass number of 1 element

Atomic mass

Number of protons in an atom

Atomic number

Location of metals and nonmetals

Metals: bottom of the staircase

Nonmetals: top of the staircase

List group number, number of valence electrons, reactivity, physical properties of: alkali metals, alkaline earth metals, halogens, noble gas, transition metals

Alkali Metals: Group 1; Valence electron: 1, Reactivity: Extremely high; Physical properties: Soft, silvery, low density, low melting points

Alkaline Earth Metals: Group 2; 2 Valence electrons; Reactvity: Very high; Physical properties: Shiny, silvery-white, harder and denser than Group 1Transition Metals: Groups 3–121 Reactivity: Moderate to low; Physical Properties: Hard, high melting points, excellent conductors

Halogens: Group 17; 7 Valence Electrons; Reactivity; Extremely high

Nonmetals: Group 18; Valence Electrons: 8 ; Physical Properties: Colourless, odourless gas

Unique feature of noble gas

Don't react with other elements

How does an ion form

Neutral atoms gain or lose electrons

Atom with electral charge

Ion

Ionic vs covalent compounds;

Consider how the bond forms, melting point, conductivity, hardness

Ionic compounds: atoms transfer electrons, creating charged ions attract each other

Melting point: high

Conductivity: high conductivity when molten or dissolved in water

Hardness: hard and brittle

Covalent Compounds: atoms share electrons to become stable

Melting point: relatively low

Conductivity: bad conductivity

Hardness: soft and flexible