Chemistry Definition and 993 Threads

Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant chemistry (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the moon (cosmochemistry), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).
Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are two types of chemical bonds: 1. primary chemical bonds e.g covalent bonds, in which atoms share one or more electron(s); ionic bonds, in which an atom donates one or more electrons to another atom to produce ions (cations and anions); metallic bonds and 2. secondary chemical bonds e.g. hydrogen bonds; Van der Waals force bonds, ion-ion interaction, ion-dipole interaction etc.

View More On Wikipedia.org
  1. ptownbro

    Figuring Subscripts in Single Replacement Equations

    Homework Statement When figuring out the product from a reaction using single replacement type of a reaction, we believe we understand what the elements and compounds will be produced but can't figure out how the subscripts are calculated/determined in some examples. #1 ZnS + O2 ---> ZnO + S...
  2. B

    Constant Volume Calorimetry - Why does (ΔnRT)=(Δn)RT

    When doing constant volume calorimetry, the enthalpy can be calculated as follows: ΔH = ΔU + Δ(PV) ΔH = w + q + Δ(PV) ΔH = PΔV + q + Δ(PV) and at constant volume: ΔH = q + VΔP which I've then see people rewrite using the ideal gas law as follows: ΔH = q + (Δn)RT where Δn is the change in...
  3. E

    Organic Chemistry Nucleophile Reactivity Rate

    CH3Br + Nu- → CH3Nu + Br- The decreasing order of the rate of the above reaction with the following nucleophiles is: [ Nu = (I) PhO- (II) AcO- (III) HO- (IV) CH3O- ] My answer is IV > III > II > I However the answer is IV > III > I > II I'm having a hard time understanding why...
  4. M

    Schools Question about Physical Chemistry Graduate School

    I'm currently a freshman a MIT. I was planning to do a Chemistry and Physics double major but after looking at the requirements for a Chemistry minor, it wouldn't take any additional classes to do a Physics and Math double major with a minor in Chemistry. The reason this is appealing to me is...
  5. CollinsArg

    I want to study Chemistry, What can I do?

    Hi! I need advices for posibilities...I'm from Argentina...I am 21...this is my situation: in my country studying in universities is free in public universities...so it is very common to start to study something and then change the major...so I first study music for a year, then I leave it and I...
  6. HeavyMetal

    Orthonormal spin functions (Szabo and Ostlund problem 2.1)

    Homework Statement [/B] Taken straight out of Szabo and Ostlund's "Quantum Chemistry" problem 2.1: Given a set of K orthonormal spatial functions, \{\psi_{i}^{\alpha}(\mathbf{r})\}, and another set of K orthonormal functions, \{\psi_{i}^{\beta}(\mathbf{r})\}, such that the first set is not...
  7. Alpha123

    What are the esters formed from fumaric acid and propanol ?

    Homework Statement what are the esters formed by: -fumaricacid and propanol? - succinic acid and butanol -citric acid and methanol and how does each one smell Homework Equations none The Attempt at a Solution I have drawn out each of the structural diagrams but i couldn't draw the esters. My...
  8. G

    Can helium prevent ozone formation in electron-plasma chemistry?

    a possible way to make superoxide oxygen anions without making ozone? please tell me, normally if there is dioxygen present and a electron emitter such as a sharp needle electrode with HV is in the dioxygen there will be mostly ozone and oxygen anions (negative oxygen ions, superoxide) formed...
  9. K

    How do I find the ph without using Hasselbach's equation?

    Homework Statement hi so in my lab class we made a buffer solution by mixing 20.00 ml of 0.100 M Sodium Hydroxide and 40.00 ml of 0.100 M of acetic acid. We then poured 15ml of this buffer solution into a beaker. So we essentially have 15 ml of this buffer solution in the beaker. We then added...
  10. R

    Coal Gasifier - Thermodynamics Question

    Homework Statement The problem is in the attached picture. I simply do not know what an "equilibrium equation" is and what it means by the composition. My professor is unbelievably difficult to get a straight, understandable answer from. I've already taken thermodynamics, but we did not learn...
  11. C

    Hydrogen Emission Spectrum, Electrons, and Quantized Energy

    I understand that the result of the hydrogen emission spectrum experiment was that only certain wavelengths of light were emitted and that led to the conclusion that electrons emit light when they relax and that they absorb light when they get excited. How does that prove that the energy for...
  12. F

    Release or absortion of energy on bonds and phase change

    I believe I can explain why there is energy needed to break intermoleculares bonds and getting into a gas or liquid, but the other way around confuses me. Bonds have potential energy associated to it, so It's needed work to break the bonds, because we would be trying to move a molecule away from...
  13. Ronie Bayron

    Classical Looking for the Best Chemistry & Physics Textbook for College?

    Hi, what's the best reference and textbook for General Chemistry and Physics in College could you recommend? I'll appreciate your recommendation.
  14. S

    Planning to take a high school Chemistry licensing exam....

    I have only took Chemistry in high school and that was about 10 years ago. So pretty much I will be starting from scratch as I certainly forgot everything. Good news is you do not need a high score on the exam to pass (72% I believe). I have about 2 months left in the US and want to take this...
  15. F

    What determines if a reaction is exotermic or endotermic?

    Using a more physics oriented approach, rather than a chemistry one, and looking to an energy point of view if possible. For example, why when ice turns into water there is a need for energy (heat)? I know in some extent that the energy is used into re-organizing the chemical bonds, but that...
  16. Garlic

    Superatom Chemistry: Where to Find Info & What's Going On?

    Hello everyone, I see that superatom chemistry was considered to be a big lap in chemistry, lots of news articles were made in 2008. The problem is, I can't find any scientific articles etc. , nothing else, but basic information on it. Even the wikipedia article of superatom chemistry is really...
  17. N

    Graviational vs Electrical Potential

    Hi all, Thanks for taking your time to help me. It means a lot! For some context: I'm a physics student taking an analytical chemistry course and am a bit confused by the concept of electrical potential. Gravitational potential is the potential energy per unit mass, V(gravitational) = U/m. (I...
  18. vision99

    What is the Impact of String Theory on Other Scientific Fields?

    Hi. I'd like to learn more about physics, and especially about how the newest discoveries are affecting other sciences, such as chemistry, computer science, electrical engineering, etc... -doug
  19. M

    How to calculate mass of air in mass balance?

    What is the general procedure for calculating the mass of air in mass balance problems? what assumptions must be made? How do i convert this into mass from a percentage, e.g 21% oxygen & 79% nitrogen?
  20. C

    Admissions Can a chemistry undergrad go to condensed matter physics?

    Hello all! I am second year undergrad at a university in US. I planned to major in chemistry and took five chemistry classes (organic and inorganic) and worked at an organic chemistry lab in my first year, but didn't really like it. After searching through all areas in chemistry and physics, I...
  21. D

    High School Students: Chemistry, Ionic/Covalent Bonds, Urea & Hydroxyurea

    I came here from https://www.physicsforums.com/threads/i-dont-understand-how-hcl-is-not-a-ionic-bond.449393/ where replies are no longer allowed. I wanted to reply to suggest a few things: High school students who like chemistry are far smarter than anyone will give them credit for. High...
  22. H

    A question about physical chemistry

    For the problem of particle in a 1D box V(x)=0 for 0≦x≦a ∞ for anywhere outside the box I know that Hamiltonian operator commutes with momentum operator so they should have smae eigenfunction but it's obvious that the wavefunction (2/a)^1/2sin(nπx/a) is not a eigenfunction of linear...
  23. D

    Golden Book of chemistry is free

    Link deleted by mentor
  24. S

    Are there any interactions from mixing these chemicals?

    Hi, So I recently got a new job, and when I was being instructed on how to close my department, I noticed that they used quite a bit of chemicals on the same surface (it's a salad bar). I was wondering if any of these chemicals could interact, and if so, what the products would be. First, the...
  25. GiantSheeps

    In what phase of matter do Neutrons/Protons/Electrons exist?

    In what phase of matter do individual Neutrons/Protons/Electrons exist? They are matter aren't they? So they must exist in some phase, right? Do they change phase? I'm very curious any information would be greatly appreciated. Thanks!
  26. Ariel Jo

    Calc ∆Ho & ∆Eo for CH3OH Reaction @ 298K

    Homework Statement For the reaction CH3OH(l) → CH4 (g)+ 1/2 O2 (g)[/B] (a) Calculate ∆Ho298 (b) Calculate ∆Eo298 (c) Write an equation that would allow you to determine ∆H at 500°C and 1atm Homework Equations ∆H=∆E+∆(PV) ∆H=Σ∆Hproducts-Σ∆Hreactants The Attempt at a Solution a)...
  27. N

    Which is the more stable structure?

    Hello! I've been trying to figure out what the most stable structure of inositol is, but I keep running into conflicting information. I'm not sure whether the most stable conformation is the myo-inositol form or the scyllo-inositol. All of the stereoisomers can be seen on wikipedia at this link...
  28. V

    Propellant Chemistry Principles

    Time and again one comes across various authors using the sentence "" by the principles of propellant chemistry"", in order to determine the ratios of the complexant (fuel, like glycene, citric acid etc) and the metal salt, in preparatioin of ferrites by sol gel technology. Say for example in...
  29. Eclair_de_XII

    Isn't chemistry just applied algebra/pre-calculus?

    The more I'm in my chemistry class, the more I feel like this is true. I'm doing all these calculations, plugging in all the appropriate values for numbers and what-not, and this has crossed my mind many times. I'm just cancelling and rearranging numbers out, in addition to units, now. I'm not...
  30. R

    Quick question on chemistry notation (mol fraction vs %)

    Hi, I have a paper that for a gas mixture writes Ar/25%O2 implying that 25% of the atmosphere of the gas is oxygen. I have another paper that writes 0.02 mol frac O2 for a Ar/CO2 atmosphere. Please could someone tell me how I would write the 0.02 mol frac O2 in the form Ar/X%CO2 and what X...
  31. E

    Self-Study Chem: Tips & Textbook Supplements

    Hi, I know that Chemistry doesn't really pertain to math or physics but I guessed this was the best website that would suit my question. Haha. I was wanting to self study general chemistry using a textbook. I do have the textbook, but was wondering what I should supplement it with. Also I was...
  32. E

    Interatomic spacing concept confusion

    I am trying to understand the concept of interatomic spacing. Below is a link to three pictures, and my questions is: why are they different? I thought atoms were packed together touching each other like in the first picture but the second and third imply otherwise. Any explanation or help is...
  33. ptownbro

    Stoichiometric relationship between liters and grams

    My daughter stump me on a question related to liters and grams in stoichiometry. Wondering if someone could help explain. First we know that 1 mole always eqauls 22.4 liters at STP. And 1 mole also always equals the selected element's atomic mass in grams on the periodic table. So... Let's...
  34. S

    Stoichiometry, find the mass of the product

    Homework Statement [/B] If 1.20 grams of salicylic acid is reacted with excess methanol, what mass of ester should you expect to achieve theoretically? Molar masses of.. salicylic acid is 138.13g/mol methanol is 32.05g/mol ester (methyl salicylate) is 152.16g/mol Mole ratio...
  35. cliffordlim

    How Does Acebutolol React with Hydrochloric Acid?

    Homework Statement What is the product form reaction of acebutolol with hydrochloric acid ? I am not sure which functional group will react with HCl Homework EquationsThe Attempt at a Solution
  36. S

    GAMESS computing and quantum chemistry

    Hi everyone, this isn't homework problem but something i would like to study and i am currently interested into. So how to start, this problem belongs more to quantum chemistry but i haven't found the topic in chemistry part of this site. I am learning to compute with program GAMESS but since...
  37. A

    The Nernst Equation- I apologize in advance for my ignorance

    Ecell = E0cell - (RT/nF)lnQ So I understand the Nernst Equation, but I don't have some info. (Please bare with me, I'm in secondary) I'm doing a Cu - Al cell. My E cell is negative (-1.33). Does this have an affect on the equation? What exactly does E0 stand for? I understand how to find E...
  38. S

    Branch of study: geology + chemistry + mathematics

    Dear fellows, I was wondering about what lies inbetween the fields of geology, chemistry and mathematics. I mean, is there a branch of study that uses the three areas? Thanks in advance. JGSeg.
  39. EthanCanSchool

    Should I Tutor My Classmate in Chemistry?

    Hi, My name's Ethan and I plan on being a teacher. I am doing good in my chemistry class with an A and a girl in my class asked if i would tutor her. This happened today. I don't if i should do it because i feel as if she won't understand what I'm saying. Should I just go for it? She also asked...
  40. GiantSheeps

    Experimental Error in Archimedes Principle Lab

    Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...
  41. wololo

    Chemistry Compare average distance between molecules to size of N2

    Homework Statement Homework Equations Pv=nRt The Attempt at a Solution I already calculated V for a single molecule = 3.99x10^-23 m^3 and the cubic root of this volume gives 3.42x10^-8 m. However, I don't understand what I should do next. What does it mean to compare the value I obtained to...
  42. reemie

    How to calculate the mass of a hydrogen atom

    The answer according to my booklet is 1.6734×10-24 (g), but I don't understand how we got this answer. proton: 1.6725×10-24 neutron: 1.6748×10-24 electron: 0.0009×10-24 To get the mass, I added protons with neutrons, but I got 3.3473×10-24. What am I doing wrong?
  43. Titan97

    Why is electron affinity positive?

    I was reading thermodynamics and about Born Haber cycle. There, I found that the values given for electron affinity are positive. When an electron is added to flourine, it attains noble gas configuration. So i t becomes more stable. So shouldn't the reaction be exothermic?
  44. Titan97

    Chemistry What are the essential topics covered in inorganic chemistry textbooks?

    I am looking for inorganic chemistry textbooks that covers topics on s,p,d block elements, metallurgy, qualitative analysis, and coordination chemistry. It should contain basic concepts like solubities of carbonates,sulphates, and should be at the level of "March's advanced organic chemistry" or...
  45. Ameer Bux

    Struggling with Stoichiometry in High School Chemistry? Here's How to Master it!

    I am experiencing some difficulty grasping some chemistry concepts pertaining to stoichometry calculations. What are the best tips for studying this section of chemistry and how can i get an intuitive feeling for these concepts? Tips on high school chemistry in general are also welcome.
  46. A

    Chemistry Which Chemistry Textbook Is Best for Introductory Courses?

    What is the best chemistry textbook for high school/college/introductory course in university? There are lots of books, such as; Atkins, Peter, Loretta Jones and Leroy Laverman. Chemical Principles: The Quest for Insight. W. H. Freeman and Company Brady, James E., and Fred Senese...
  47. Titan97

    Why is k4 Greater than k3 in Cadmium Complex Formation?

    Homework Statement The formation of cadmium complexes with Br- exhibits successive equilibrium constants such that log(k1)=1.56, log(k2)=0.54, log(k3)=0.05, log(k4)=0.37. Explain why k4 is greater than k3 Homework Equations $$K=e^{\frac{-\Delta H}{RT}}\cdot e^{\frac{\Delta S}{R}}$$ The...
  48. Titan97

    Chemistry Books on physical chemistry by Atkins

    I saw many books on physical chemistry by Peter Atkins. 1)Elements of Physical chemistry by Peter Atkins and Julio De Paula 2)Physical Chemistry by Peter Atkins and Julio De Paula 3)Chemical Pricnciples - A quest for insight by Peter Atkins and Loretta Jones Which book should I use for learning...
  49. Q

    Why do different gases have different densities?

    I've read that gas molecules do not have any attractions or regulations between them... So why do different gases have different densities?
  50. H

    Is it possible to create a protest gas that sedates and lasts a long time?

    Is it possible to create a protest gas that sedates and lasts for a very long period but has a limit on its severity, no matter how long exposed? If so, may you please elaborate? This is for fiction I'm working on.
Back
Top