How to Draw a Lewis Structure

A Lewis structure is a graphic representation of the electron distribution around atoms. The reason for learning to draw Lewis structures is to predict the number and type of bonds that may be formed around an atom. A Lewis structure also helps to make a prediction about the geometry of a molecule. Chemistry students are often confused by the models, but drawing Lewis structures can be a straightforward process if the proper steps are followed. Be aware there are several different strategies for constructing Lewis structures. These instructions outline the Kelter strategy to draw Lewis structures for molecules. Step 1: Find the Total Number of Valence Electrons In this step, add up the total number of valence electrons from all the atoms in the molecule. Step 2: Find the Number of Electrons  Needed to Make the Atoms Happy An atom is considered happy if the atoms outer electron shell is filled. Elements up to period four on the periodic table need eight electrons to fill their outer electron shell. This property is often known as the octet rule. Step 3: Determine the number of bonds in the molecule Covalent bonds are formed when one electron from each atom forms an electron pair. Step 2 tells how many electrons are needed and Step 1 is how many electrons you have. Subtracting the number in Step 1 from the number in Step 2 gives you the number of electrons needed to complete the octets. Each bond formed requires two electrons, so the number of bonds is half the number of electrons needed, or: (Step 2 - Step 1)/2 Step 4: Choose a Central Atom The central atom of a molecule is usually the least electronegative atom or the atom with the highest valence. To find electronegativity, either rely on periodic table trends or else consult a table that lists electronegativity values. Electronegativity decreases moving down a group on the periodic table and tends to increase moving from left to right across a period. Hydrogen and halogen atoms tend to appear on the outside of the molecule and are rarely the central atom. Step 5: Draw a Skeletal Structure Connect the atoms to the central atom with a straight line representing a bond between the two atoms. The central atom can have up to four other atoms connected to it. Step 6: Place Electrons Around Outside Atoms Complete the octets around each of the outer atoms. If there are not enough electrons to complete the octets, the skeletal structure from step 5 is incorrect. Try a different arrangement. Initially, this may require some trial an error. As you gain experience, it will become easier to predict skeletal structures. Step 7: Place Remaining Electrons Around the Central Atom Complete the octet for the central atom with the remaining electrons. If there are any bonds left over from Step 3, create double bonds with lone pairs on outside atoms. A double bond is represented by two solid lines drawn between a pair of atoms. If there are more than eight electrons on the central atom and the atom is not one of the exceptions to the octet rule, the number of valence atoms in Step 1 may have been counted incorrectly. This will complete the Lewis dot structure for the molecule. Lewis Structures vs Real Molecules While Lewis structures are useful, especially when youre learning about valence, oxidation states, and bonding, there are many exceptions to the rules in the real world. Atoms seek to fill or half-fill their valence electron shell. However, atoms can and do form molecules that are not ideally stable. In some cases, the central atom can form more than other atoms connected to it. Also, the number of valence electrons can exceed 8, especially for higher atomic numbers. Lewis structures are helpful for light elements but less useful for transition metals, including lanthanides and actinides. Students are cautioned to remember Lewis structures are a valuable tool for learning about and predicting the behavior of atoms in molecules, but they are imperfect representations of real electron activity.

Short Story Chapter 1 - 1321 Words

â€Å"Yes, Captain I am fine with that.† â€Å"Okay, you are dismissed, if you have any questions or concerns, please don’t hesitate, come straight to me.† â€Å"Don’t worry Captain if I have any questions I am sure Warren here will help me out.† He said with a dazzling smile and the first words I heard him speak. His country drawl hung deep in his words when he spoke. He clearly didn’t live around here his whole life. With that I got to my feet and left the Captain’s office and headed for my desk. He followed me like a lost puppy and pulled up a chair from another desk and sat with the back of the chair to his chest. â€Å"So, partner what do we got in store today?† He said with a sly smile on his face. â€Å"We don’t have anything to do, but I have something†¦show more content†¦I wanted to smack that smile off his face. I stared at him for a few minutes and realized that people were starting to stare and I felt my cheeks heat. I walked over to the elevator and hesitated, I really didn’t want to be trapped on there with him. So, I veered to the right and made my way down the stairs to the case file room. He followed me even though he stopped and looked at the elevator. He shrugged and kept going behind me. When we got down to the file room there was an officer sitting at the desk behind the locked gate. â€Å"Hey Warren† he stood up and dusted the chip crumbs from his uniform. His name was Stanley Upton and he was a good cop, but he stammered a lot when he spoke to me. He was about ten years older than me and put down here since he was shot on the job during a bank robbery five years back. I ignored the chip crumbs that he had still in his beard and smiled at him. â€Å"Hey Upton, I am here to sign out a cold case and I am showing the new Detective around the station. This is Detective Ford, Ford this officer Upton.† Upton’s smiled faded for just a second. Clearly not excited to see the new handsome Detective strutting around the station. That makes two of us. Upton handed me the sign in sheet and a bin to place our guns in, then he hit the buzzer to unlock the gate. â€Å"Do you need me to look up the case number and show you where it is?† â€Å"No, Upton I have looked into this case a few times I know exactly where itShow MoreRelatedShort Story : A Short Chapter : Chapter 1971 Words   |  4 PagesIse said nothing though she did raise an eyebrow. Naoko coughed nervously and continued, â€Å"It’s just an idea but I’d like to at least try it out to see if it’ll even work and since you’re said to be really god with kidÃ…  I thought you could help me.† Ise’s face still looked unamused though when she spoke there was a hint of interest in her voice, â€Å"How did you come up with that idea?† The teen shrugged, â€Å"I read about a weapon Quincies have used called Seele Schneider. 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The clang rang off the stone walls which echoed loud enough to surly raise the dead at the very least to alert the household as was the intent. Duncan stepped back to let the door swing outward, whichRead MoreShort Story : A Short Chapter : Chapter 12137 Words   |  9 Pagesbrothers got in and went back to the motel. â€Å"Fay gets the bed,† Sam was about to protest when Dean quickly shut him up. â€Å"She stabbed a ghost in the eye twice, killed him, made friends with a ghost, and saved both our asses,† Fay just grabbed her black shorts and tank then walked into the bathroom. Stripping down, she turned on the hot water, letting the warmed rinse off the dirt and grime from the asylum. Turning off the water, she grabbed her toothbrush. As she got out the toothpaste there was a knockRead MoreShort Story : A Short Chapter : Chapter 12195 Words   |  9 Pageshappened to me would be considered within parameters. From there, they let me out of the machine and I faked being Sister long enough to be sent on my way.† Finishing off my water I set it down and nervously licked my lips. â€Å"And that’s basically my story. After leaving I got a new kit, put myself up in a hotel and over the next few days I wandered around, saw the city, did some research, and experimented a bit with being an Esper... Any questions?† Mikoto and Kuroko stared at each other and at Mikoto’sRead MoreShort Story Chapter 11266 Words   |  6 Pagesfright. Drakes smirk grew as he noticed this. You dont have a choice. As soon as those words made their way into the dead air he bolted towards the other boy. Shadow pushed Jace behind him and braced for the incoming attack, and not like other stories, this one hit its mark. He winced, and noted the body behind him. Activating the pipes in his calves he dashed towards a clearing only to take a fireball to the back. Come back and fight me coward! Drake was catching up fast. 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Perhaps we might find suitable lodgings afterwards?† Seeing Gwen’s reluctance to put her out further in her eyes, Blancheflor insisted, â€Å"You are my guestRead MoreChapter 1 : A Short Story1136 Words   |  5 PagesKaterina stepped out of the shadow of the filing cabinet. She pushed her hood down and swung her sniper off of her back before leaning it against the wall. â€Å"Hey Maria.† She said as she placed the suitcase onto agent Hills desk. The brunette glanced at her before she looked back to her computer screen and continued to type. â€Å"Hello, Shadow.† The young woman snorted and quickly appeared next Hill, slinging an arm over her shoulders. â€Å"Oh, don’t be like that. You know calling me ‘Agent Volkova’ overRead MoreShort Story : Chapter 11085 Words   |  5 PagesThe pillow seemed to sink a little, and Johnny died. I looked towards Dally, his face turned ten times younger, his face, his hard, mean, face had tears rolling down it. â€Å"...Johnny†¦Ã¢â‚¬  his voice whispered faintly, but Johnny said nothing. He could not. Dally had a pained expression that only someone who knew him could recognize, his hands were in fists. â€Å"We’re leaving,† Dally demanded, â€Å"Wait† the nurse said jogging towards us, â€Å"Johnny wanted you to have this.† she handed me Gone With the Wind. I took

Symptoms And Symptoms Of Alzheimer s Disease - 1642 Words

Abstract Alzheimer’s disease is a brain disorder when brain cells degenerate and die. Alzheimer’s dieses destroys the patient’s memory within time. The mental functions of the brain also get destroyed when a person gets Alzheimer’s. Alzheimer’s disease is most commonly seen when the patient is sixty to seventy years old. In this research paper the reader will learn about the signs and symptoms, causes, course of disease, outcome and secondary diagnosis, treatment, and prognosis and survival. Signs and Symptoms There are several different ways to tell if a person has or is getting Alzheimer’s disease. There are ten early signs and symptoms of Alzheimer’s disease. The first symptom is memory loss. Memory loss is the most common symptom. People with Alzheimer’s disease tend to forget new things, names, and dates of important events such as anniversaries or birthdates. Another thing that Alzheimer’s effects with memory is the short term part. This will make people with Alzheimer’s disease ask questions over and over again in anchors amount of time in between. The second symptom is having trouble to plan or solve problems, or completing familiar tasks at home. This is where it is hard for the people who have Alzheimer’s disease it is hard for them to do simple tasks such as cooking or following a recipe. Also, working with numbers such as paying the bills or balancing a checkbook. People with Alzheimer’s disease may a lso have trouble with doing the simpleShow MoreRelatedSymptoms And Symptoms Of Alzheimer s Disease930 Words   |  4 PagesAlzheimer’s Disease Kevin Arnold from the Wonder Years said â€Å"Memory is a way of holding on to the things you love, the things you are, and the things never want to lose.† Memories are the things that are upheld, whether good or bad, those memories are imprinted in the mind and cannot be taken away that is, until later in life. As one ages it is natural for some memories to fade. Loss of memories and brain function deficits that occur and are not from normal aging may indicate a person is sufferingRead MoreSymptoms And Symptoms Of Alzheimer s Disease3214 Words   |  13 Pages NEU ID: 001983161 Donepezil and other acetylcholinesterase inhibitors in Alzheimer’s disease Abstract: Alzheimer’s disease (AD), discovered by Dr. Alois Alzheimer in 1907, is the most common form of dementia. The early symptom of Alzheimer’s disease is having difficulty in remembering recent events. At the advanced stage, the signs and symptoms of AD include: memory loss, confusion, trouble concentrating, frustration, irritability difficulty in saying, difficultyRead MoreSymptoms And Symptoms Of Alzheimer s Disease2317 Words   |  10 Pagesthey age and the various experiences they go through. One of the most common diseases among older people is dementia. Among the different types of dementia, the most prevalent one is Alzheimer’s disease (AD). 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Moby Dick Characters of Captain Ahab and Ishmael Essay Example For Students

Moby Dick Characters of Captain Ahab and Ishmael Essay Moby Dick Essays Moby Dick Characters of Captain Ahab and Ishmael The characters of captain Ahab and Ishmael are almost opposites. About the only things the two share in common are that they are both seamen and they both are on a hunt for a whale. Ishmael is a pleasing character, who plays the role of the main character as well as narrator. He is a common man who has a love for the sea, and goes to it to clear his mind whenever he feels down or feels that it is a damp, drizzly November in his soul. As for his physical appearance, he doesnt really specify. However, one might assume that he is a middle-aged man and probably holds the characteristics of the stereotypical seaman. But, what the character lacks in physical description, he makes up for with a full personality that his described extensively throughout the book. Ishmael is a man who seeks what is best described as inner peace. He is very content with himself when on the water, and has a great love for being a seaman. He joins the crew of the Pequod to satisfy his longing to be back on the ocean, but as it turns out, the particular voyage he is to set out on is not what he had suspected. For this ship would be commanded by a half-crazed captain in a desperate search for a viscous white whale. Over all, Ishmael is definitely the most civilized and wise man in the story. Captain Ahab is an overwhelmingly intimidating character in the story, and can probably be considered the most deranged of them all. His radical obsession with finding and killing the white whale known as Moby-Dick causes Ishmael and others of the crew to become frightened at his abnormal behavior. Ahabs physical appearance is best described as foreboding and evil. He is a tall man with gray hair, and is missing a leg due to a death-defying confrontation with Moby-Dick himself. His new artificial leg is made from the bone of whale and once again adds to his intimidating form. His personality is also quite mad. He has a maniacal presence about him and would risk his life and the lives of his crewmen just to fulfill his mission of demented revenge. Melville does a fine job describing this particular character with the utmost extremeness. The characters of Ishmael and Ahab are two that have a great and critical impact on the book. Ishmaels character allows the reader to relate to a love for nature and the earth, as well as a feeling of inner peace and serenity. While on the other hand, Ahabs character is one of chaos and udder madness. The two characters attitudes, thoughts, and feelings permit the reader to explore two polar opposites of the human personality. Ahabs character is critical to the story element in that without him, the reader could not really experience the insaneness of the voyage and the cruelty of the mission that they have set out to accomplish. On the other hand, without the character of Ishmael, the reader would not know how to react to Ahab, and furthermore would only be able too experience one side of the voyage. The reader would be unable to relate to Ahabs demented character, and therefore would have no one in the story to relate themselves to. Ishmaels character gives the reader someone to relate to and identify with. All in all, both characters let the reader better understand the story, and allow for an intense reading experience.