Chemistry: Chapter 7 Flashcards
valence electron
electrons in the highest energy level of an element’s atoms
cations
positively charged; loses valence electrons
anions
negatively charged; gains valence electrons
how to find the number of valence electrons in an element?
look at its group number
electron dot structure
diagrams that show valence electrons for atoms of an element as dots
electron dot structure
diagrams that show valence electrons for atoms of an element as dots
the octet rule
states that in forming compounds, atoms tend to achieve the electron configuration of a noble gas (8 valence electrons)
the octet rule
states that in forming compounds, atoms tend to achieve the electron configuration of a noble gas (8 valence electrons)
metals….
tend to lose valence electrons (+ charge)
non metals…
tend to gain valence electrons (- charge)
sodium…= (2)
non reactive; stable in water
transition metals….
silver = example
look at last two thingies of a transition metal’s electron configuration and determine how many valence electrons it would take to get to 8.
ex. Silver - 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s1 <– either lose 11, or gain 7!!!!
what does an anion’s name end with?
- ide
ex. Na + Cl = sodium chlorIDE
Halide ions
ions produced when atoms of chlorine and other halogens GAIN electrons
ionic compound
compound composed of cations and anions
ionic compound
compound composed of cations and anions
what is the charge of an ionic compound?
electrically neutral, b/c the charge of the cations are equal to the charge of anions
what is the charge of an ionic compound?
electrically neutral, b/c the charge of the cations are equal to the charge of anions
ionic bonds
the electrostatic forces that hold ions together in ionic compounds
ionic bonds
the electrostatic forces that hold ions together in ionic compounds
what attracts anions to cations?
electrostatic forces
what attracts anions to cations?
electrostatic forces
chemical formula
shows the numbers of atoms of each element in the smallest representative unit of a substance
Ex. Sodium chloride = NaCl
formula unit
the lowest whole-number ratio of ions in an ionic compound
formula unit
the lowest whole-number ratio of ions in an ionic compound
3 properties of ionic compounds?
- they are crystalline solids at room temperature
- high melting points
- can conduct an electric current when melted or dissolved in water
coordination number
the number of ions of opposite charge that surround the ion in a crystal
coordination number***
the number of ions of opposite charge that surround the ion in a crystal
metallic bond
the forces of attraction between the free floating valence electrons and the positively charged metal ions
how can you model the valence electrons of metal atoms?
as a sea of electrons
properties of metals (3)
good conductors of electric current - b/c electrons can flow freely in the metal
ductile and malleable - b/c of the mobility of valence electrons
if an ionic crystal is struck with a hammer, positive with be pushed together (since they repel each other, the crystal would shatter)
describe the crystalline structure of a metal
they are arranged in very compact and orderly patterns
for spheres of identical size, there are many possible arrangements, the three most common ones are body-centered cubic, face-centered cubic, and hexagonal close-packed
describe the crystalline structure of a metal
they are arranged in very compact and orderly patterns
for spheres of identical size, there are many possible arrangements, the three most common ones are body-centered cubic, face-centered cubic, and hexagonal close-packed
body-centered cubic arrangement (2)
what elements? (4)
every atom, except those on the surface, have 8 neighbors
elements that are in this arrangement: SODIUM, POTASSIUM, IRON, CHROMIUM, AND TUNGSTEN
body-centered cubic arrangement (2)
what elements?
every atom, except those on the surface, have 8 neighbors
elements that are in this arrangement: SODIUM, POTASSIUM, IRON, CHROMIUM, AND TUNGSTEN
face-centered cubic arrangement (2)
what elements? (5)
every atom has 12 neighbors
elements: COPPER, SILVER, GOLD, ALUMINUM, AND LEAD
face-centered cubic arrangement (2)
what elements?
every atom has 12 neighbors
elements: COPPER, SILVER, GOLD, ALUMINUM, AND LEAD
hexagonal close-packed arrangement (2)
what elements? (3)
atoms also have 12 neighbors; the difference is the pattern
elements: MAGNESIUM, ZINC, AND CANDIUM
hexagonal close-packed arrangement (2)
what elements?
atoms also have 12 neighbors; the difference is the pattern
elements: MAGNESIUM, ZINC, AND CANDIUM
alloys
mixtures of two or more elements, at lease one of which is a metal
why are alloys important?
b/c their properties are often superior to those of their component elements
most important alloys today?
steels
principal elements in most steels? (9)
iron, carbon, boron, chromium, manganese, molybdenum, nickel, tungsten, and vanadium.
properties of steel?
corrosion resistance
ductile
hardness and toughness
substitutional alloy
when atoms of the components in an alloy are about the same size, so they replace each other in the crystal
interstitial alloy
if the atomic sizes are quite different, the smaller atoms can fit into the spaces (interstices) between the larger atoms
Who developed the octet rule?
Gilbert Lewis
steels are what kind of an alloy?
an interstitial alloy
steels are what kind of an alloy?
an interstitial alloy
How many valence electrons does helium have?
2 valence electrons
Non gases are…
Non reactive –> stable
Ionization
Process of gaining or losing valence electrons / electrons
What is the name of selenium as an anion?
Selenide
Describe how ionic compounds conduct electricity
When melted, the crystalline structure breaks down and if a voltage is applied across this melted compound, cations will be free to roam to one electrode to the other and anions migrate to the other. This movement allows an electric current to flow between the electrodes through an external wire
What type of alloy is steel?
An Interstitial alloy
How do ionic compounds conduct electric current when dissolved in water ?
Same as when the compounds are melted except they are able to migrate around in the solution (water)
Metals consist of… (cations and valence electrons)
Closely packed cations and loosely held valence electrons
What holds metals together ?
Metallic bonds
How do you explain the ductility and malleability of metals?
By the loose mobility of the valence electrons
Why are ionic compounds brittle?
Because when it is struck with a hammer in crystalline form, the blow tends to push the positive ions close together and since they repel each other, the crystal shatters
How are metals arranged?
In very compact and orderly patterns
How do you explain the ductility and malleability of metals?
By the loose mobility of the valence electrons
What kind of metals are crystalline? (2)
Metals that contain just one kind of atom
It’s the most simple form of all crystalline solids
What is brass made up of? (2)
Copper and zinc
How are metals arranged?
In very compact and orderly patterns
What is Sterling silver made up of? (elements) (2)
Silver and copper
What kind of metals are crystalline? (2)
Metals that contain just one kind of atom
It’s the most simple form of all crystalline solids
Elements that make up bronze? (2)
Copper and tin
What alloys make coins? (3)
What are they called? (1)
Bronze, copper-nickel, and aluminum alloys
They are called nonferrous alloys
What is brass made up of?
Copper and zinc
What elements make up cast iron? (2)
Iron and carbon
What elements make up stainless steel ? (3)
Iron
Chromium
Carbon
Nickel
Elements that make up bronze?
Copper and tin
What alloys make coins?
What are they called?
Bronze, copper-nickel, and aluminum alloys
They are called nonferrous alloys
What elements make up cast iron?
Iron and carbon
What elements make up stainless steel ?
Iron
Chromium
Carbon
Nickel
