Chemistry 9 Flashcards
What is chemistry
Study of matter + its interactions
Pure substance
One type of particle
Mixture
Two or more pure substances (tow or more particles)
Mixtures (elements/compounds)
Elements/compounds not chemically combined
Compounds
Atoms of two or more elements combined in a definite proportion (cannot be separated by chemical means)
Elements
One type of atom and cannot be broken down by chemical means
Homogenous mixture
When a mixture is so uniformly mixed you cannot microscopely tell it apart (air, steel)
Heterogeneous mixture
When a mixture is not so uniformly distributed, you can see the different parts
Chemical properties
Characteristics that describe the ability of matter to react with another substance to form one or more different substances
Physical properties
Characteristics that can be observed of measured without changing its chemical identity
List at least 3 chemical properties
Combustibility, reactivity with acids, reactivity with oxygen, lack of reaction
List at least 3 physical properties
Colour, malleability, texture, viscosity, conductivity, state of matter, melting, boiling point, hardness, solubility
Atomic number
Z
Refers to the number of protons in an atom in a particular element
Groups
Vertical column of elements (1-18)
Periods
Horizontal row of elements (1-7)
Atomic mass
Average mass of an atom
Properties of Metals (At least 3)
Good conductors of heat/electricity Malleable Ductile Shiny when pure and unreacted High melting/boiling points Loose electrons to form + charged ions (cations)
Nonmetals (at least 3)
Poor conductors of heat/electricity Brittle Low densities Low melting/boiling points Non-ductile Gain electrons (anions)
Metalloids (at least 3)
Mostly solid Can be shiny/dull May conduct electricity Poor heat conductors Brittle, non-ductile
Transition metals
Elements from group 3-12 on the periodic table
3 common properties: metal, form colourful compounds and catalysts
Can form ions with different charges
Subatomic particles
Positive protons
Negative neutrons
Solve for mass number
Sum of protons and neutrons
Number of electrons equals…
Number of protons
What is an atom called if it gains or looses an electron
An ion
Describe a bohr model
Shell 1 = 2 electrons
Shell 2 = 8 electrons
Shell 3 = 18 electrons
[ electrons are arranged in shells around the nucleus - certain # of electrons allowed in each shell ]
How do you make a Bohr model of an ion (example: Fluorine)
Fluorine - 9 protons
Has more than 4 electrons on the outermost shell (valence)
line [ bohr model of fluorine ] line
Add one minus because it has to LOOSE the electron to become fluorine again
Now called a fluoride anion
Outer valence shell must have 8 electrons
How do you know if a ion gains or looses
VALENCE SHELL
Less than 4 - loose
More than 4 - gain
Ex. Fluorine would GAIN because it has MORE THAN 4 electrons on the valence shell
Metals don’t change their name, non-metals do (T/F)
True
Diatomic elements
Elements found in groups of two
N2, O2, F2, Cl2, I2, Br2
hockey stick
Group 1 elements: Proterties
Further you go down = more reactive
Halogens
Group 17
Non-metals
Low melting/boiling points, poor electrical conductors
Formerly known as group 7 (7 valence electrons
Reactivity: Group 17
Atomic radius increases as it goes down- Wants to grain a valence electron- decrease in reactivity halogens
Less valence shells at top, increase in reactivity
The easier it is to gain/lose an electron…..
The more reactive it is
Properties of transition metals
Less reactive than group 1 and 2
Similarities exist as we move across a period rather than down a group`
Inert gases
Noble gases are known as this ebcause they do not react with anything
Shielding
The decrease in attraction between an electron and the nucleus in any atom with more than one in electron shell
Octet rule
The tendency of an electron to gain a valence shell with a total of 8 electrons
Naming simple ionic compounds: Lithium and nitrogen
Name: Lithium nitride
Formula: Li 1+, N3-
Add three more Li’s to balance out the charges
= Li3N
Anions always change their names (T/F)
True
-ide
Ionic compounds with multivalent elements
Same as simple ionic compounds, but pay attention to the roman numerals.
Polyatomic ions
Same as simple ionic compounds, however, if the polyatomic ion is used more than once put a bracket around
Ex. Mg(OH)2
Covalent compounds (Ex. Co2 and oxygen difluoride)
Two non-metals
Carbon dioxide
Di because there are two oxygens
OF2
Dissociate and associate
D; To dissolve
A: To come together
Properties of ionic compounds
Conducts electricity when molten Hard High melting point Non-conductor hen solid Brittle
