Chem mod 3 journal
List the steps to naming a covalent compound.
1: Add a prefix to the name of the first element to represent the number of atoms of the element in the bond (needed if there is more than one). For N2O4, the beginning is dinitrogen. 2: Add a prefix to represent the number of atoms of the second element to the root of the second element's name. For N2O4, the second element will be tetrox- (not tetraox-). 3: Add the ending -ide to the last element. N2O4 is dinitrogen tetroxide.
What steps should you follow to write a chemical formula for an ionic compound?
1: identify the charge of each of the ions in the compounds 2: write the caption first, followed by the anion. for most ionic compounds, this corresponds to the locations of metals and nonmetals. 3: determine the ratio of positive to negative ions needed to make the compound neutral 4: make sure the subscripts represent the lowest whole number ratio for the ionic compound. 5:Make sure the net charge of the formula is zero. Take the charge of each ion multiplied by its subscript, and then add them together.
What are the steps to create Lewis dot diagrams to show bonding?
1: write the lewis dot notation for aluminum and sulfer 2: draw arrows to show the transfer of electrons 3: assign charges to the ions 4: write the unit formula based on the charges.
Describe what occurs in and results from a molecule being polar.
When a molecule is polar, a separation in electrical charge causes opposite electrical charges on opposing sides of the molecule.
Ionic bonds form when one or more ________ are transferred between two atoms.
electrons
The atoms of elements can lose, gain, or even share _______. How many are needed for stable configurations?
electrons
The outermost shell is the energy level that contains ________ in an atom.
electrons
3.02
ionic bonding
compound consistency
ionic: brittle covalent: soft
melthing and boiling point
ionic: high covalent: low
dissolve in water
ionic: yes covalent: varies
elements within bond
ionic:metals with nonmetals Covalent: nonmetals with nonmetals
Metals tend to _____ electrons and nonmetals tend to ____ electrons to give them full valence shells like a noble gas.
lose
Dipole-dipole
Dipole-dipole forces are electrostatic interactions of permanent dipoles in polar molecules. Since opposites attract, the positive end of one polar molecule and the negative end of another polar molecule tend to align the molecules to increase the attractio
Why does nitrogen form three covalent bonds when it bonds to another nitrogen?
Each nitrogen atom can share three electrons with another nitrogen atom to fill their valence shells with eight electrons.
Why does oxygen form two covalent bonds when it bonds to another oxygen?
Each oxygen atom needs two additional electrons to fill its valence shell. Two oxygen atoms form a double bond
How do permanent dipoles compare to dispersion forces and temporary dipoles in terms of formation and strength?
The forces and attractions between polar molecules cause adjacent molecules to align with one another. This is an example of a dipole interaction.
What forces create the bent triatomic shape of a water molecule?
The shape of a water molecule is determined by the repulsion of all its electron pairs, including the oxygen atoms' unshared pairs of electrons
How do the intermolecular forces between molecules affect the boiling point of a substance?
The stronger the intermolecular forces, the greater the energy required to pull the molecules apart and enter the vapor phase, which means they have a higher boiling point.
What are dipoles, and how are they formed?
The unequal sharing of electrons within a bond leads to the formation of an electric dipole. dipoles-a separation of positive and negative electric charges.
How do hydrogen bonds form between water molecules
. The weakly or partially positive hydrogen end of one molecule is attracted to the weakly or partially negative oxygen of another molecule, and hydrogen bonds form.
Describe the three dipole types and how they are formed.
1. Permanent Dipoles.These occur when atoms in a molecule have substantially different electronegativity and form polar bonds 2.instantaneous dipoles. These chance occurrences happen when moving electrons are briefly more concentrated in one place than another within a molecule, creating a temporary dipole. 3.induced dipoles. These temporary dipoles can occur when one molecule with a permanent dipole repels another molecule's electrons, "inducing" a dipole moment in that molecule temporarily.
Ionic bonds, which involve the transfer of electrons, occur when the difference in electronegativity between two elements exceeds ______ on the Pauling scale.
1.6
Any bond with an electronegativity difference of less than ____ is a covalent bond.
1.7
Bonds that have a difference in electronegativity ranging from ____ to ____ are ionic bonds
1.7/ 4.0
Using the slide show examples, explain how to create a noble gas notation to represent the valence electrons of an element.
1.Find the last element (the noble gas in Group 18) from the previous row on the periodic table. The noble gas at the end of the row above Cl is Neon (Ne), so this is the symbol that is used in the shorthand resolution. Write the symbol of that element in brackets. [Ne]2.Cl's electron configuration is 1s22s22p63s23p5. [Ne] represents the 1s22s22p6of the configuration. Write the rest of the element's notation to complete that element's shorthand notation. [Ne] 3s23p
How many electrons are in the valence shell of noble gases?
8 electrons
How do scientist predict the polarity of molecules?
A molecule will be polar if two conditions are met. 1st the bonds in the molecule must be polar. This is determined via the difference in electronegativity between the two atoms bonded. If the difference is 0.4 or larger, the bond will be polar
The greater the difference in their electronegativity values, the more ______ the chemical bond between two atoms
ionic
How do polyatomic ions form ionic bonds with other elements? Provide an example from the lesson.
As the name suggests, a polyatomic ion is made up of more than one atom bonded together covalently, but has an overall positive or negative charge (ion) because electrons have been gained or lost
What causes electronegativity to decrease going down a group?
As we head down the groups of the periodic table, electronegativity decreases due to the shielding effect of the inner electrons
What causes electronegativity to increase going left to right on the periodic table?
As we move from left to right across the periodic table, electronegativity increases as more protons are added to the nucleus and the electrons are added to the same valence shell.
What is ionization energy?
the energy required to remove an electron from an atom
What is a general pattern to determine bond type based on element type?
Beryllium and chlorine are far apart from one another on the periodic table. But don't be fooled; the electronegativity of beryllium is 1.57, and the electronegativity of chlorine is 3.16; the difference between them is 1.59, which is below the 1.7 electronegativity difference threshold for ionic bonds. Beryllium chloride (BeCl2) forms a covalent bond
How do covalent bonds form?
Covalent bonds form between atoms of similar electronegativities
What is a diatomic ion?
Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements.
Describe double bonds.
Double covalent bonds involve two shared pairs of electrons.
What is electronegativity?
Electronegativity is almost the exact reverse of ionization energy
How does electronegativity determine the bonding behavior of an element?
Electronegativity measures the tendency of an atom to attract electrons. It is a property of an atom when it is joined to another atom in a chemical bond.
________ and ________ energy influence the attractive forces between ions that form ionic bonds
Electronegativity/ Ionization
What is the first thing you should do to determine whether a chemical formula represents an ionic or covalent bond?
Elements with a difference in electronegativity lower than 1.7 will bond covalently.Elements with a difference in electronegativity above 1.7 will bond ionically.
How is ionization energy used to predict the charges of ions? Use an example from the video.
Four atoms and their electrons are shown. Sodium atom is shown with a graph of ionization energy per electron. A valence electron leaves the sodium atom and enters the chlorine atom. Together they form a solid structure as more atoms form a fixed pattern, and table salt is shown.
Describe what you learned about valence electrons for each group of the periodic table.
Groups 1 and 2: All the elements in column one have one valence electron in their outermost shell. Transition metals:The transition metals follow unique rules, so their columns cannot directly tell us about their total valence electrons. groups 3-7:Just like columns one and two, taller columns three through seven indicate the number of valence electrons for the elements within them group 8: With the exception of helium, which only needs two electrons to fill its outermost shell, all other elements in column eight have eight valence electrons.
Nonmetals have a ____ electronegativity except for the noble gases, which are assigned an electronegativity of _____.
High/ zero
Why it is important to consider the VSEPR model of an atom when determining the polarity of a molecule?
However, a molecule will not have a permanent dipole moment if the molecular arrangement is symmetrical
Hydrogen bonding
Hydrogen bonds are strong dipole-dipole interactions, not actual bonds. They only occur between molecules containing N-H, O-H, or F-H bonds. Hydrogen forms highly polar covalent bonds with the highly electronegative elements N, O, and F. Hydrogen's small atomic radius allows two molecules containing these polar bonds to come in very close contact with each other, increasing the attraction between the dipoles of each molecule.
How can you remember the seven diatomic elements?
I Bring Clay For Our New House Iodine, Bromine, Chlorine, Fluorine, Oxygen, Nitrogen, Hydrogen.
What types of multiple bonds exist?
If an element can form more than one bond, it can do so with multiple single bonds or make a double bond or triple bond.
How are ionic compounds with polyatomic ions named?
If the negative ion in the compound is a polyatomic ion, just name the polyatomic ion using the list—do not change its ending to -ide.
When are prefixes not used for naming covalent compounds?
If there is only one atom of the first element in the compound, no prefix is used
Describe what happens in the video when two hydrogen atoms come close together.
If two hydrogen atoms come close together, the electron of each atom is attracted to the positively charged nucleus of the other.
If two hydrogen atoms come close together, the electron of each atom is attracted to the positively charged nucleus of the other.
If two hydrogen atoms come close together, the electron of each atom is attracted to the positively charged nucleus of the other.
Explain how electrons interact in covalent bonds
In compounds held together by covalent bonds, electrons do not migrate from one atom to another. Instead, they are ______________________________ by the atoms.
Hydrogen and helium don't follow the octet rule. Why? (Hint: Think about the capacity of the first energy level of an atom.)
In the specific case of hydrogen, we notice that it has only one positively charged proton. Since electrons bear equal but opposite charges to protons, it is now understandable that H could host only a few extra electrons while maintaining appreciable stability.
Why does it take less energy to evaporate a liquid than to break the bonds within molecules?
Intermolecular forces are usually much weaker than intramolecular forces.
Name some of the important molecules made possible by hydrogen bonding.
Intramolecular hydrogen bonding is partly responsible for the secondary, tertiary, and quaternary structures of proteins and nucleic acids, key molecules important to sustaining life
How are ionic and covalent bonds different?
Ionic bonds involve the TRANSFER of one or more electrons from one atom to another. Covalent bonds involve the SHARING of one or more electrons between atoms.
bonding
Ionic: transfer of electrons Covalent bonds: sharing of electrons
Why are transition metals more "eager" to react with substances than transition metals to the right of the periodic table?
It wants the other 7 electrons.
How can you determine an ion's charge from its group position on the periodic table?
Just as the periodic table was your guide for valence electrons, it also helps you determine the ionic charges of the main group elements.
List the four types of intermolecular forces in order of strength.
London dispersion, dipole-dipole, hydrogen bonding, and ion-dipole forces
how do nonmetal atoms gain a full valence shell?
Nonmetal atoms share electrons by overlapping half-filled orbitals from their valence shells. This gives both atoms in the covalent a full valence shell of eight electrons.
distribution of nonpolar molecules?
Nonpolar molecules have an even distribution of charge due to all nonpolar bonds, or symmetrical polar bonds that "cancel out."
Metals have a ______charge equal to the number of valence electrons they _____.
Positive/ lose
What do prefixes represent when naming covalent compounds?
Prefixes are used to represent the subscript on each of the elements in the molecule on each of the elements in the molecule.
Why are valence electrons mostly found in the s and p sublevels of the outermost energy level in an atom?
S and P subshells don't have the same challenges as other subshells.
Describe the reactivity of sodium-group 1, carbon-group 4, chlorine- group 7.
Sodium-group 1: highly reactive carbon-group 4:less reactive chlorine-group 7:highly reactive
When is there an exception to the covalent naming system?
Sometimes, covalent compounds are named using Roman numerals when the metal bonding covalently is a transition metal, which can share different numbers of electrons depending on the bond.
What repulsion forces create the Tetrahedron shape of a molecule?
The bonding electron pairs have like charges and repel each other. They adopt a molecular arrangement ( tetrahedron shape) that minimizes this repulsion.
How does ionization energy determine the bonding behavior of an element?
The difference in first ionization energies determines the type of bond that will form between two elements.
How is the electron geometry of a molecule determined?
The electron geometry of a molecule is determined by the number of bonded electrons and lone pair electrons around the central atom
Explain how position on the periodic table relates to an element's reactivity.
The farther right and up you go on the periodic table, the higher the electronegativity, resulting in a more vigorous exchange of electron.
Why does hydrogen form a single bond with another hydrogen?
The hydrogen atom has only one electron, which is its valence electron. It can only share what it has, which is a single electron. So when hydrogen atoms bond with other atoms, they can only form a single bond.
Combine lithium and neon. Why don't they bond together?
They will not bond. neon is a noble gas and has 8 electrons.
Describe dipole moments with molecules
This polarity creates a net electrical charge within the molecule, or dipole moment.
Explain what happens as more electrons are shared between atoms.
When more electrons are shared between the two atoms, the bond is stronger and the atoms are pulled closer together, making the bond shorter.
Describe how polar covalent bonds are formed.
When nonmetals share their electrons unequally, meaning one atom has a higher electronegativity than the other
Describe how atoms with a large difference in electronegativity form ionic bonds.
When two atoms have a large difference in electronegativity, the atom with the greater electronegativity can take one or more electrons from the other atom
How do intermolecular forces compare to intramolecular forces?
atoms are held together by intramolecular forces to form chemical compounds. forces of attraction between separate molecules, called intermolecular forces.
What is the benefit of using Lewis dot structures to represent valence electrons?
You can use Lewis dot notation as a visual to help you predict how an element will gain, lose, or share electrons to achieve a full valence of eight electrons.
What are polyatomic ions, and what type of bond holds the elements of a polyatomic ion together?
a charged group of covalently bonded atoms. a group of atoms bond together with covalent bonds by sharing electrons but have an overall positive or negative charge
What is a chemical formula? Include an example and label the subscripts.
a formula giving the number of atoms of each of the elements present in one molecule of a compound
Define chemical bond
a link between two atoms resulting from the mutual attraction of their nuclei for valence electrons
Combine sodium and fluorine. Describe how they bond
a single electron from the outermost orbit of sodium will move into the outermost orbit of fluorine. Sodium now becomes a positively charged atom whereas fluorine now has a negative charge. The two atoms now move together but their orbits do not overlap.
Describe covalent bonds.
also called a molecular bond, is a chemical bond that involves the sharing of electron pairs between atoms.
Ion-dipole
attractive forces that result from the electrostatic attraction between an ionic compound and a polar molecule, commonly found in solutions. Because there is a full charge on the ions and a partial charge on the dipole molecules, ion-dipole forces are stronger than dipole-dipole forces, but not as strong as ionic bonds. For example, when NaCl is added to water, the cation (Na+) is attracted to the partially negative end of the water polar molecule, while the anion (Cl−) is attracted to the partially positive end.
Describe the differences between cations, anions, and neutral atoms
cations- In an atom that loses electrons, protons outnumber the electrons and the atom becomes a positively charged cation. anions-If the atom gains electrons, the electrons outnumber the protons and form a negatively charged anion. atoms-Atoms are neutral when the numbers of protons and electrons are equal and their charges balance each other
Why do scientists use noble gas configurations to represent valence electrons?
chemists are only concerned with an atom's valence electrons, because those are the electrons that are more involved with bondingand other chemical properties
3.03
covalent bonding
Electron pairs exist in many positions, or ________ around a central atom. How is this number determined?
domains
Illustrate the arrangement of nitrogen's valence electrons using electron configurations.
electron configuration: 1s22s22p3 valence electrons: 5
Describe the steps used to create Lewis dot structures to represent covalent bonds.
first count how many valence electrons you have in total from all of the atoms that will be bonded. Then, determine how many atoms of each element are needed to satisfy the octet rule for each atom. Place the least electronegative element (farthest from the top right corner of the periodic table) in the center of the molecule.
3.06
forces and bonds
What are intermolecular forces?
forces of attraction between separate molecules,
Tetrahedral
four domains: could have 4, 3, or 2 bonded atoms. 0,1, or 2 lone pairs. shape could be tetrahedral, trigonal pyramidal, bent, structure is tetrahedral. Tetrahedral molecules exist in four domains. A molecule with four domains could have the following configurations: four bonded atoms and zero lone pairs on the central atom (AX4) three bonded atoms and one lone pair on the central atom (AX3E) two bonded atoms and two lone pairs on the central atom (AX2E2) one bonded atom and three lone pairs on the central atom (AXE3)
What is the VSEPR molecule shape? is it the same as or different from the electron geometry for a molecule?
general shape that considers the repulsive and attractive forces between electron pairs. More often than not, the VSEPR shape and electron geometry are different for a molecule.
What do the delta symbols on polar molecules represent?
he delta symbols indicate that the charges are weak compared to those charges carried by ions.
If the valence electrons equal eight, the element is ________. What does this mean regarding reactivity
inert. Which means it doesn't react with other substances.
3.05
molecular structure
How is the Roman numeral system, also known as the Stock system, used to name compounds with transition metals? Give an example.
names the charge of the ion in parentheses in the compound's name.
Nonmetals have a _______ charge equal to the number of electrons they need to ______ to fill their valence shell.
negative/ add
3.04
nomenclature
Dispersion
occur between all molecules and particles but are the only force of attraction between nonpolar molecules or noble gas atoms. These forces are the weakest of the intermolecular forces. London dispersion forces are temporary attractive forces that result when adjacent molecules form instantaneous, or temporary, dipoles.
Describe how nonpolar covalent bonds are formed.
occurs if the bonded atoms are the same element or have very similar electronegativity values
Linear
one domain: central atom has 1 bond. shape/ structure: linear.A molecule with one domain will have a total of one bonded atom and zero lone pairs on the central atom A molecule with two domains will have a total of one bonded atom and one lone pair on the central atom, or two bonded atoms and zero lone pairs on the central atom.
When one element has higher electronegativity than another, such as in a water molecule, what happens?
oxygen pulls the shared electrons more strongly than hydrogen, creating a slightly negative charge for the oxygen and slightly positive for the hydrogen. These cancel out but create a polar covalent bond.
How do you determine the number of atoms of each element in a compound that includes a polyatomic ion enclosed in parentheses?
simply multiply the subscript of each individual atom by the subscript outside the parentheses.
Describe the octet rule
states that atoms for elements in the main element groups prefer to have up to eight valence electrons
What special properties does hydrogen bonding give to water?
surface tension is so high and how liquid water is able to spread like a film, pool into droplets, and remain in droplets on vertical surfaces like a window despite the downward pull of gravity.
What did Lewis's octet rule propose?
the atoms of all elements had between one and eight electrons in their outermost, or valence, shell.
Explain the relationship between valence electrons and bonding.
the atoms of other elements can lose, gain, or even share electrons to achieve the stable configuration of eight electrons in their valence shell.This transfer of electrons is what we know today as a chemical reaction and results in bonds between atoms,
How do ion charges differ for the fourth main group column and the transition metals?
the charge of elements in the fourth main group column depends on the bond they form with other elements.
What is a formula unit?
the formula of an ionic compound that represents the simplest whole number ratio of ions in the compound, not the actual number of each ion present in the crystal
When a substance is heated, what bonds are broken? What bonds are not broken?
the less energy the molecules have. Raise the temperature, or in this case heat ice until it melts, and it is the intermolecular forces that are broken. The molecules themselves are unchanged.
Why do substances stick together?
the molecules in the are attracted to one another by something called van der Waals forces. These forces keep liquids together, and they work because of dipoles. An electric dipole is a pair of opposite charges separated by distance.
Describe the number of covalent bonds.
the number of covalent bonds an atom can form is usually equal to the number of electrons it needs to fill its valence shell
Elements in the first group of the periodic table have just one electron in their outer shell. Describe the pattern for the other tall columns.
the second group, has two; boron, three; carbon, four; and so on
Combine hydrogen and fluorine. Describe how they bond.
their outermost electron orbits overlap. One electron from each of their outer orbits started orbiting both nuclei.
How do van der Waals forces hold molecules together?
they work because of dipoles. An electric dipole is a pair of opposite charges separated by distance.
triginal planar
three domains: could have 2 or 3 bonded atoms. shape could be trigonal planar or bent, structure is trigonal planar. A molecule with three domains will have three possible chemical formulas and configurations around the central atom. three bonded atoms and zero lone pairs (AX3) two bonded atoms and one lone pair (AX2E) one bonded atom and two lone pairs (AXE2)
What elements can form more than one possible charge as positive ions?
transition metals in the d block, as well as tin (Sn) and lead (Pb)
describe triple bonds
triple bonds involve three shared pairs of electrons
Whether ionic or covalent, what does bonding always involve?
valence electrons
How do you use electronegativity to determine bond type?
when the electronegativity difference is greater than 2.0, the bond is considered ionic. if it's less than 0.5, then the bond is nonpolar covalent
