Start Of Sem Review Flashcards
What is an element
Cannot he broken down further and still have those properties
What is a compound
Contains atoms in fixed proportions, can be broken down further
- ionic compounds
- molecular compounds
What is a solution
Homogenous mixture
Can only see 1 phase
What is a mechanical mixture
Heterogenous mixture
Multiple phases are visible
What is a physical change
Does not produce a new substance
Size change
Change in state
Shape
What is a chemical change
Produces a new substance
Precipitation forms
Emits heat or light or absorbs it
Gas bubbles
Unexpected change in color
Hard to reverse
Change in color
How did Dmitri Mendeleev arrange a table of known elements
By atomic mass
How is the now periodic table arranged
By atomic number
What is periodic law
When elements are arranged by atomic number, their chemical and physical properties recur periodically, showing trends
What are period
Rows
Electrons occupy same number of shells
What are groups
Electrons in balance shell (outer shell)
These e- give similar chemical and physical properties
Describe metals
Solid at room temp except hg
Shiny
Conductors (heat/electricity)
Malleable
Ductile
Describe non metals
Solid liquid or gas at room temp
Non conductors
Brittle solids
Describe metalloids
Show both properties
Shiny solids, brittle, poor conductors
What are alkali metals
Period 1
Soft metals
Very reactive with water, not found in nature
React easy with halogens “xy”
