The Definition of a Solid in Chemistry and Science

The Definition of a Solid in Chemistry and Science A  solid is a  state of matter characterized by particles arranged such that their shape and volume are relatively stable. The constituents of a solid tend to be packed together much closer than the particles in a gas or liquid. The reason a solid has a rigid shape is that the atoms or molecules are tightly connected via chemical bonds. The bonding may produce either a regular lattice (as seen in ice, metals, and crystals) or an amorphous shape (as seen in glass or amorphous carbon).  A solid is one of the four fundamental states of matter, along with liquids, gases, and plasma. Solid state physics and solid state chemistry are two branches of science dedicated to studying the properties and synthesis of solids. Examples of Solids The matter with a defined shape and volume is solid. There are many examples: A brickA pennyA piece of woodA chunk of aluminum metal (or any metal at room temperature except mercury)Diamond (and most other crystals) Examples of things that are not solids include liquid water, air, liquid crystals, hydrogen gas, and smoke. Classes of Solids The different types of chemical bonds that join the particles in solids exert characteristic forces that can be used to classify solids. Ionic bonds (e.g. in table salt or NaCl) are strong bonds that often result in crystalline structures that may dissociate to form ions in water. Covalent bonds (e.g., in sugar or sucrose) involve the sharing of valence electrons. Electrons in metals seem to flow because of metallic bonding. Organic compounds often contain covalent bonds and interactions between separate portions of the molecule due to van der Waals forces. Major classes of solids include: Minerals:  Minerals are natural solids formed by geological processes. A mineral has a uniform structure. Examples include diamond, salts, and mica.Metals:  Solid metals include elements (e.g., silver) and alloys (e.g., steel). Metals are typically hard, ductile, malleable, and excellent conductors of heat and electricity.Ceramics:  Ceramics are solids consisting of inorganic compounds, usually oxides. Ceramics tend to be hard, brittle, and corrosions include silicon and gallium arsenide. Nanomaterials:  Nanomaterials are tiny solid particles at the nanometer size. These solids may display very different physical and chemical properties from large-scale versions of the same materials. or example, gold nanoparticles are red and melt at a lower temperature than gold metal.Biomaterials:  These are natural materials, such as collagen and bone, that are often capable of self-assembly.

Free Older Official ACT Practice Tests

Free Older Official ACT Practice Tests SAT / ACT Prep Online Guides and Tips There’s one thing that every student studying for the ACT definitely needs: practice tests that are almost identical to what you will face on your test day. No matter how else you study, we've found that most students really benefit from practicing by taking the full ACT test severaltimes in as close to test-taking conditions as possible. This is the best way to get comfortable with the format, timing and pace, your own endurance, and ways to manage your stress. So how do you get your hands on enough ACT tests to put yourself in the hot seat for practice? In this article, I’ll link to all the official tests and question sets released by ACT, and give you suggestions on where to find others, so that you have more than enough practice materials to get ready for the ACT. Why Use Old Official ACT Tests to Study? The good news about the ACT is that althoughits design has undergone some changes in the past few years, older tests are still verysimilar to the one you'll be taking. This means that you should still definitely try your best to use official ACT tests to study instead of the ones written by other companies. What Has Changed on the ACT? Though the basic format of the ACT has stayed the same for the past few decades, ACT, Inc. has made some recent revisions. First, the ACT Reading section now sometimes includes aset of paired passages, with multiple choice questions that compare and contrast them. If you're worried about this new style of passage, we have some advice on how to approachthe paired passage section of ACT Reading, as well as some commiseration on what makes this part of the test hard. Second, the ACT Writing section now features an expanded promptandan increased focus on your ability to analyze differing points of view. There have also beensome adjustments to the way it's scored. For all the details, read our full breakdown of all changes on the new enhanced ACT Writing test. Why Are Official ACT Tests Still Your Best Option? Now, let me explain why official tests are better than those written by other companies. Official tests released by ACT are made up of questions from older tests that have been retired. This means that they’ve gone through the same writing and editing process as the questions you'll see on test day. In other words, they are the real thing. On the other hand, other companies might be good at mimicking ACT style, or they might not be. If you stick to official ACT tests, you will put yourself in the position of having to judge the authenticity of style, wording, or approach of third-party work. Ifound my true self inAuthenti City on our last vacation, just aftera fewshocking days in Electri City and a spy tour of Dupli City. Free Official Test Links Here is a list of all of the full official ACT tests that have been released in the past 14 years. They are in PDF format, and you should print them out totake the test on paper just like you will on test day. Wondering why the 14-year list has fewer than 14 tests? ACT, Inc. releases the same practice test several years in a row. I’ve included the form number of each test so you can always tell whether you’ve already seen this test or not. You can find form numbers in the bottom left-hand corner of each ACT test page. ACT Practice Test and Answers (2018-2019)- form number 74F Test: p-55. Answer key: p57-60. ACT Practice Test and Answers (2015-2016)- form number 72C Test: p-55. Answer key: p57-62. ACT Practice Test and Answers (2014-2015)- form number67C Test: p-51 (ignore the essay). Answer key: p56-62. ACT Practice Test and Answers (20-2012)- form number64E Test: p13-56 (ignore the essay). Answer key: p60-65. ACT Practice Test and Answers (2008-2009)- form number61C Test: p13-55 (ignore the essay). Answer key: p60-64. ACT Practice Test and Answers (2005-2006)- form number59F Test: p13-55 (ignore the essay). Answer key: p60-65. Free Practice Question Sets From ACT In addition to releasing a fullofficial test every two years, ACT, Inc. publishes practice question sets on its website. If you countthem, you'll see that these practice questions make up another completeACT. But I don't recommend usingthem for yourtest-day conditions practice sessions. For one thing, the actual test will be in hard copy and not online. Moreover, on the ACT site, the correct answers to the practice questions pop up immediately after you click your answer choice. Believe me, that will not happen on your actual test booklet. Instead, use the online practice questionsto work onskills and to boost your comfort level with the different ACT test sections. 75 ACT English questions 60 ACT Math questions 48 ACT Reading questions 40 ACT Science questions 1 ACT Writing prompt with 6 graded sample essays ACT Question of the Day(keep scrolling down the page until you see it) Other Potential Official ACT Sources Find ACTtestsfor free on the internet.There are plenty of official old ACT tests that have not actually been published by ACT available online. Most of these are photocopies of actual past tests, which means they aren't authorized to be distributed, and that the websites they are on are breaking some intellectual property and copyright rules. I don't think you'll be at much risk if you decide to use them, but I'd advise you not to announce this fact over your school's loudspeaker. To find them, run a search for â€Å"free old act tests† and look for less commercial sites. Since you have theform numbers for the authorized, you can see which tests you haven’t taken or seen before. Maybe save the heralds for announcing your awesome ACT score, not broadcasting your internet searches for unauthorized practice tests. Buy ACT test books. If you have the resources, there are two great sources for ACT tests that you can buy: The first is the bookThe Official Guide to the ACT, 2019-2020 edition. It features5 official ACT tests and costs about $17 usedon Amazon. You can also check whetheryour library has a copy- just make sure it doesn't have the answers written into it. The second is theACT Online Program. It has two practice tests and costs $25 from ACT. We would advise you to skip their prep material, which is neither customized to you nor organized for the most effective studying. What’s the Best Way to Use These Tests? Now that you've downloaded all the ACT practice tests I linked to above, how do you make sure you're using them in the best and most effective way? Here are some suggestions. Work inas close to test-day conditions as possible. It makes sense that the more practice you have with how the test will actually go on the day you take it for real, the more prepared you'll be: Print the tests out andwork on paper. Work in a quiet room, without music or other interruptions and distractions. Time yourself ruthlessly and stop working on a section if your time runs out. You need to know if you are having trouble with pacing, so you can figure out how to stop running out of time on the math, science, reading, or writing section. Take the whole thing in one sitting. It’sa marathon 4 hours, so you need to get used to it, with justthe breaks that the real test with allow Take the test this waymore than once. In my experience, the 3rd or 4th time you take it is when you become sofamiliar with the format that takingthe testbecomes second nature. Review your answers in order to learn from your mistakes. Once you identify problem areas, use other kinds of test prep to honeyour skills (check out our guide to figuring out which ACT prep method is best for you). The wrong place to take your practice test. What’s Next? Need to know whether to retake the ACT? We can help you decide. Wondering how to study for the ACT? Check out the complete study plan we developed to know when you should take the ACT tests and when to study. Read our extensive guide on what it takes to get a 36 on the ACT, written by a perfect scorer. Also, read our in-depth strategy approaches togetting a 36 on ACT English, ACT Math, ACT Science,ACT Reading, and the ACT Writing essay. Want to improve your ACT score by 4+ points? Download our free guide to the top 5 strategies you need in your prep to improve your ACT score dramatically.