CHAPTER FOUR: COMPOUNDS AND THEIR BONDS Flashcards
In nature, _________ ________ the elements on the Periodic Table are found in combination with other atoms.
Only the atoms of the ________ _______ do not combine in nature with other atoms.
Almost all
Noble gases
What is a COMPOUND?
In a typical IONIC COMPOUND, one or more ____________ are transferred from the atoms of metals to atoms of ___________.
The attraction that results is called an ___________ __________.
A compound is a pure substance composed of two or more elements with a definite composition.
ELECTRONS, NONMETALS
IONIC BOND
In compounds of NONMETALS, _________ bonding occurs by atoms sharing one or more ___________ electrons.
COVALENT bonding
VALENCE electrons
Are COVALENT or IONIC compounds more prevalent?
COVALENT
COVALENT COMPOUNDS consist of ____________ which are discrete groups of __________.
MOLECULES; ATOMS
IONIC BONDS occur when atoms of one element _______________ and the atoms of another element __________________.
LOSE valence electrons
GAIN valence electrons
COVALENT BONDS occur when atoms of nonmetals _______________.
SHARE valence electrons.
The NOBLE GASES are so stable that they form compounds only ______________.
Why are they so stable?
under extreme conditions.
They have 8 valence electrons
What is the OCTET RULE?
The tendency for atoms to attain a noble gas electron arrangement is known as the OCTET RULE and provides a key to our understanding of the ways in which atoms bond and form compounds.
Describe IONIC BONDING.
A METAL atom readily loses valence electrons. In doing so, a metal atom obtains the same electron arrangement as its nearest __________ _________ (usually ____ valence electrons).
By losing electrons, a metal atom forms an _____, which has a positive charge.
In IONIC BONDING, ions, which have electrical charges, form when atoms lose or gain electrons to form OCTETS.
NOBLE GAS; 8
ION
What is an IONIC CHARGE?
the difference between the number of protons (positive charge) and the number of electrons (negative charge)
What are CATIONS?
Metals in ionic compounds lose their valence electrons to form positively charged ions called CATIONS
A metal ion is named by its ____________ ________. Thus Mg^2+ is named the _____ _______.
A metal ion is named by its ELEMENT NAME.
magnesium ion
The ionization energy of a NONMETAL atom in Group 5A, 6A or 7A is ________.
Rather than _____ electrons in an ionic compound, a NONMETAL atom ______ one or more valence electrons to attain an ______.
In doing so, a nonmetal atom obtains the same electron arrangement as its nearest _____ ______ and forms a __________- charged ion.
HIGH
LOSE; GAINS; OCTET
NOBLE GAS; NEGATIVELY
A negatively charged ion, also called an _________, is named by using the first syllable of its name followed by ______
ANION
ide
We can obtain the number of valence electrons of the REPRESENTATIVE ELEMENTS from the ________ ___________ on the Periodic Table.
We can also use those to determine the _____ _______ for most of the ions.
Group 1A- lose _____ electron to form ions with a _____ charge
What about the same for Group 2A, 3A?
GROUP NUMBERS
IONIC CHARGES
1A- lose 1 electron to form ions with a 1+ charge
2A- lose 2 electr. to form ions with a 2+ charge
3A- lose 3 electr. to form ions with a 3+ charge
In IONIC COMPOUNDS the atoms of the elements in Group 7A ___ (gain or lose?) ___ (how many?) electron(s) to form ions with a _______ charge.
How about the elements in:
- Group 6A
- Group 5A
GAIN ONE electron; form ions with a 1- charge
6A- gain 2 electr. to form ions with a 2- charge
5A- gain 3 electr. to form ions with a 2- charge
The NONMETALS of Group 4A ______ (do or do not) typically form ions.
The metals Sn and Pb in Group 4A _____ electrons to form _______ ions.
DO NOT
LOSE; POSITIVE
IONIC COMPOUNDS consist of ______ and ______ ions, held together by strong attractions between the oppositely charge ions, called ________ __________.
POSITIVE; NEGATIVE
IONIC BONDS
The physical and chemical properties of an ionic compound are ______ ________ ________ those of the original elements.
Very different from
What accounts for the high melting points of ionic compounds?
At room temperature, ionic compounds are ________.
There are many strong attractions between the positive and negative ions.
SOLIDS
What do we mean when we say “the FORMULA of an ionic compound”?
The sum of the ionic charges in the formula is always _______, which means that the ____________.
This indicates the number and kinds of ions that make up the ionic compound.
ZERO, which means that the total amount of positive charge is equal to the total amount of negative charge.
Ex: the formula NaCl indicates that the compound consists of one sodium ion, Na+, for every chloride ion, Cl-. Although th ions are positively or negatively charged, their ionic charges are not shown in the formula of the compound.
Explain how SUBSCRIPTS are used in formulas of ionic compounds. Use magnesium and chlorine as an example.
Ex: To achieve an octet, a MG atom loses its 2 valence electrons to form Mg^ 2+. Two Cl atoms each gain one electron to form 2 Cl- ions.
The 2 Cl- ions are needed to balance the positive charge of Mg^2+. This gives the formula MgCl2 (the 2 is subscript), magnesium chloride, in which a subscript of 2 shows that 2 Cl- are needed for CHARGE BALANCE
The subscripts in the formula of an ionic compound represent the number of ______ and ______ ions that give an overall charge of ______.
POSITIVE; NEGATIVE
ZERO
What is a FORMULA UNIT?
In the formula of an ionic compound, the _______ is written first, followed by the _____.
Ex: write the formula of the ionic compound containing Na+ and S2- ions.
A FORMULA UNIT is the lowest ratio of the ions in an ionic compound.
The CATION is written first, followed by the ANION.
Ex: write the formula of the ionic compound containing Na+ and S2- ions:
To balance the ionic charge of the S2- ion, we will need to place 2 Na+ ions in the formula. This gives the formula Na(sub)2S, which has an overall charge of zero.
Naming IONIC COMPOUNDS:
- metal ions
- nonmetal ions
- any compound
The name of a METAL is the same as its elemental name.
The name of a NONMETAL ION is obtained by using the first syllable of its elemental name, followed by ide.
In the name of any COMPOUND, a ______ separates the name of the metal ion from the name of the nonmetal ion.
How do we name IONIC COMPOUNDS containing 2 elements?
Are subscripts mentioned? Why?
In the name of an ionic compound made up of two elements, the name of the METAL ION is given first, followed by the name of the NONMETAL ION.
SUBSCRIPTS are NEVER mentioned. They are understood as a result of the charge balance of the ions in the compound.
What are the FOUR steps to naming ionic compounds with metals that form a single ion?
- Identify the CATION and ANION.
- Name the CATION by its element name.
- Name the ANION by using the first syllable of its element name followed by ide.
- Write the name of the CATION first and the name of the ANION second.
It is not as easy to determine the charge of a TRANSITION ELEMENT because they typically form two or more positive ions. They _______ electrons from the ______ energy level and sometimes from a ______ energy level as well.
This is also true for metals of REPRESENTATIVE ELEMENTS in groups ____ and ______.
LOSE electrons from the HIGHEST energy level and sometimes from a LOWER energy level as well.
Groups 4A and 5A, such as Pb, Sn and Bi
What is VARIABLE CHARGE?
In this case, can we predict the ionic charge from the group number?
When a metal can form two or more types of ions, it has VARIABLE CHARGE.
Ex:
- Iron has two forms Fe^2+ and Fe^3+
- Copper has two forms Cu+ and Cu2+
We CANNOT predict the ionic charge from the group number, in this case.
When different ions are possible, a naming system is used to identify the particular CATION. How does this work?
A Roman numeral that is equal to the ionic charge is placed in parentheses immediately after the elemental name.
Ex: Fe^2+ is iron(II) and Fe^3+ is iron(III)
The TRANSITION ELEMENTS form more than one positive ion except for _______, _______ and ________, which form only one ion.
zinc (Zn^2+)
cadmium (Cd^2+)
silver (Ag+)
Thus, only the elemental names of zinc, cadmium and silver are sufficient when naming their cations in ionic compounds.
Metals in Groups _____ and _____ also form more than one type of positive ion.
4A and 5A
Ex: lead and tin in Group 4A form cations with charges of 2+ and 4+
When you name an ionic compound, you need to determine if the metal is a _______ or a __________.
If it is a TRANSITION ELEMENT, you will need to use __________ as part of its name, except for ______, ________ or silver.
REPRESENTATIVE ELEMENT or a TRANSITION ELEMENT.
…use its IONIC CHARGE as a ROMAN NUMERAL…
….except for zinc, cadmium or silver.
Ex: We use CHARGE BALANCE to determine the charge of a copper cation in the ionic compound CuCl2. Because there are 2 chloride ions, each with a 1- charge, the total negative charge is 2-. To balance this, the copper ion must have a charge or 2+, or Cu^2+. To indicate the 2+ charge for the copper ion Cu^2+, we place the Roman Numeral (II) immediately after copper when naming this compound: copper (II) chloride . (see page 135-136 in text)