chem ch 7.8.9
Why might you want to use alloys instead of the pure elemental form of an element?
Alloys typically have superior properties to their elemental counterparts.
Name the following base: Al(OH)3
Answer: Aluminum hydroxide Explanation: Since it is a base, you use your ion chart. The 3 goes with aluminum, so Al 3+ and OH-.
Name this compound: CaBr₂. What type of compound is it?
Answer: Calcium Bromide, ionic compound Explanation: This compound contains calcium (Ca) and bromine (Br). Calcium is a metal (it is in Group 2A, which means its a metal). Since there is a metal present, it is an ionic compound, meaning that ions are present. The ions are Ca 2+ (Group 2A) and Br - (Group 7A). Refer back to previous chapters to remember how to determine their charges. After you determine their ions, use your ion chart to name them. Remember, the cation comes first, the anion second.
Write the formula for "carbonic acid".
Answer: H2CO3 Explanation: Using your ion chart, you know it is an acid, so you have to have a "H". CO3 is the anion and named carbonate. Its ionic charge is 2-, so that 2 goes with the H.
Name the following acid: HBr
Answer: Hydrobromic acid Explanation: Since the anion in HBr is "Br-", called bromide, it ends in an -ide, which is changed to -ic. Also, since it ends in -ide, you add hydro- to the front as a prefix
Name the following acid: H2S
Answer: Hydrosulfuric acid Explanation: The anion in H2S is "S 2-". Since "S 2-" is sulfide, and it ends in -ide, change -ide to -ic and add hydro- as a prefix.
Write the formula for this compound: phosphoric acid. What type of compound is it?
Answer: H₃PO₄, acidic compound Explanation: This compound is an acid because it says so. Since it says acid, it must have at least one hydrogen (H). The ion for it is H+, your cation. Therefore the anion must be PO₄. The compound's name ends in -ic and it does not say hydro- in the front, indicatig that the ion should end in -ate. The ion is name phosphate and is PO₄ 3-. Switching the charges, you are left with the formula listed above.
Name the following base: Pb(OH)2
Answer: Lead(II) hydroxide Explanation: Since it is a base, just use your ion chart. Pb(OH)2 has lead (Pb) and there is a 2, so it is lead (II) and add hydroxide.
Name the following base: LiOH
Answer: Lithium hydroxide Explanation: Since it is a base, you just use your ion chart. Li is named lithium and OH is named hydroxide.
Name the following acid: HNO2
Answer: Nitrous acid Explanation: The anion on HNO2 is "NO2 -", called nitrite. Since it ends in a -ite, you change the ending to -ous.
Name this compound: H₂SO₄. What type of compound is it?
Answer: Sulfuric acid, acidic compound Explanation: There is a "H" in the front, indicating that it is an acid. Since it is an acid, you know that the "H" is the cation and the rest of the compound is the anion, SO4, and since the H has a subscript of 2, the charge for SO4 is 2-. So, you use your ion chart to find SO4 2-, which is named "sulfate". If the anion ends in -ate, you change it to -ic and add acid to the stem, in this case sulfur, to become sulfuric acid.
Hydrogen and oxygen react to form two compounds, Compound A and Compound B. Compound A contains 3.80 grams of hydrogen and 5.60 grams of oxygen. Compound B contains 5.40 grams of hydrogen and 7.90 grams of oxygen. What is the whole-number mass ratio of this reaction?
Answer: The mass ratio is 1:1 for hydrogen to oxygen. Explanation:Compound A => 3.80 g H / 5.60 g O = 0.679 g H per 1.00 g OCompound B => 5.40 g H / 7.90 g 0 = 0.684 g H per 1.00 g OMass ratio => 0.679 g H / 0.684 g H = 0.993 / 1 = 1 / 1 => 1:1
Write the chemical formula for gold (III) oxide.
Au2O3
Write the chemical formula for barium hyroxide
Ba(OH)2
Write the formula for calcium carbonate.
CaCO3. since calcium and carbonate both have charge of 2 they cancel out. Oxygen still keeps the 3.
How do you find the ionic charge of an element?
The ionic charge can be found based on the group number of the element. Group 1 is always +1, Group 2 is +2, Group 3 is +3, Group 4 is +4 or -4, Group 5 is -3, Group 6 is -2, Group 7 is -1, and Group 8 is 0.
What is the difference between metals found on the periodic table and metals not found on the periodic table, such as steel?
The metals found on the periodic table are elements and therefore only one atom. They are the purest form of metals. Examples include Iron, Copper, and Aluminum. Other metals, such as steel, are alloys and not found on the periodic table because they are actually either compounds or mixtures, meaning they are mixed with other elements. For example, steel is a mixture of Iron and Carbon.
How can you tell if an element on the periodic table forms a cation or an anion?
The metals in Group 1A, 2A, and 3A (the first three columns, skipping the transition metals) all form cations. Transition metals also form cations. The nonmetals in Groups 5A, 6A, and 7A all form anions. Group 4A may form either. (look at group #)
When drawing electron dot structures, the number of dots is the same as _____.
The number of dots is the same as the number of valence electrons. (group #)
How are polar covalent and nonpolar covalent bonds similar? How are they different?
They are similar because they are both covalent bonds (i.e. they share electrons and lack ions), however, they differ because polar bonds share electrons unequally and pull the electrons at a greater strength than nonpolar covalent bonds.
Why don't the noble gases react with other elements?
They are the most stable due to having the maximum number of valence electrons their outer shell can hold.
Tell whether the following compound is molecular or ionic. Write its formula. Compound: Iron (III) oxide
This compound is ionic. it has the metal iron in it and Roman Numerals, which are only used for writing ionic compounds, specifically ions for transition metals. The formula is Fe2O3.
Tell whether the following compound is molecular or ionic. Write its name. Compound: PBr3
This compound is molecular. There are no metals present and no ions. The name of the compound is phosphorus tribromide.
When writing the formula for an ionic compound, what goes first, the cation or the anion?
Traditionally, we write the cation (+) first and then the anion (-), because cations are simplier than anions, which may include polyatomic ions.
How do you name transition metal cations?
Use the name of the metal followed by Roman numerals of the number of electrons lost. For example, if iron loses 2 electrons, we call it Iron (II) ion.
What is the molecular formula for the binary molecular compound iodine heptafluoride?
IF7
How do you find how many valence electrons are in an atom of an element?
the group number
How do you name cations?
using the name of the metal followed by the word "ion". For example, sodium becomes a "sodium ion".
Write the chemical formula and name the compound using the ions Fe 2+ and PO4 3-
Fe3 (PO42)
What is the name for the binary molecular compound S2F10?
Disulfur Decaflouride
How do you know if a compound is an acid?
It haves one or more hydrogen (H) atoms in the compound. The hydrogen is placed in the front of the compound.
Is the following compound an acid or a base? Name it. Compound: Fe(OH)3
It is a base, since it has a hydroxide (OH) in it. Its name is iron (III) hydroxide.
Is the following compound an acid or a base? Name it. Compound: KOH
It is basic because it has a hydroxide in it. The name is potassium hydroxide.
How do we represent molecular compounds? How do we represent ionic compounds?
Molecular compounds are represented by the entire molecule. Ionic compounds are represented by the ions used to form the compound
What is the difference between a molecule and a compound?
Molecules are elements that share electrons in order to bond. Compounds are molecules that consist of two or more different elements bonded together. Not all molecules are compounds, but all non-ionic compounds are molecules.
What is the molecular formula for the binary molecular compound dinitrogen tetroxide?
N2O4
Do some elements exist as single atoms?
Yes, some elements, such as those in the noble gas grouping, exist as single atoms without bonding. The reason is because these elements have their outermost energy levels filled and are more stable. All of the noble gases have 8 valence electrons, except Helium, which has only 2.
How can you determine the ionic charge of an element?
You can determine the ionic charge of an element by looking at group number and subtracting it by 8. transition metals don't follow this method.
How do you know if a compound is an base?
if it is ionic and has a hydroxide (OH) within it. The hydroxide appears at the end of the compound since it is always the anion.
An ionic compound is a compound consisting of what?
it is a compound formed from a cation and an anion bonding together.
How do you name anions?
named by altering the ending of the element using -ide. For example, oxygen become an "oxide ion".
