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assignments --unit 3 part 5

chemical formulas

ionic compounds

covalent compounds

Students with computer systems - take notes and also carry out methods for each section

Students without computers - take notes and do review concerns in each section

Chemical Formula

The usage of chemical signs and also subscripts to reexisting aspects in a compound.

You are watching: Which of the following chemical formulas shows an ionic compound?

· Define chemical formula.

· Exordinary just how to compose a chemical formula.

· Identify the proportion of differentelementsin a compound from its chemical formula.

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You deserve to make a straightforward salad dressing utilizing simply the two ingredients pictured above: oil and vinegar. Recipes for oil-and-vinegar salad dressing differ, but they frequently encompass about 3 components oil to one part vinegar, or a proportion of 3:1. For instance, if you wanted to make a cup of salad dressing, you could mix togethercup of oil andcup of vinegar. Chemicalcompoundslikewise have actually “ingredients” in a specific ratio. However, unfavor oil-and-vinegar salad dressing, a chemical compound always has exactly the same proportion ofaspects. This ratio deserve to be represented by a chemical formula.

RepresentingCompounds

In achemical formula, theelementsin a compound are stood for by their chemical signs, and the proportion of various aspects is represented by subscripts. Consider the compoundwatperiods an instance. Each water molecule consists of 2 hydrogenatomsand one oxygen atom. As such, the chemical formula for water is:

H2O

The submanuscript 2 after the H mirrors that there are twoatomsof hydrogen in the molecule. The O for oxygen has no subscript. When there is just one atom of an element in a molecule, no submanuscript is offered in the chemical formula.

Formulas for Ionic and also CovalentCompounds

TheTablebelowreflects four examples of compounds and also their chemical formulas. The initially 2 compounds are ionic compounds, and also the second two are covalent compounds. Each formula mirrors the ratio ofionsoratomsthat comprise the compound.

Name of Compound

Type of Compound

Ratio ofIonsor Atoms of Each Element

Chemical Formulas

Sodium chloride

ionic

1 sodium ion (Na+) 1 chloride ion (Cl-)

NaCl

Calcium iodide

ionic

1 calcium ion (Ca2+) 2 iodideions(I-)

CaI2

Hydrogen peroxide

covalent

2 hydrogen atoms (H) 2 oxygen atoms (O)

H2O2

Carbon dioxide

covalent

1 carbon atom (C) 2 oxygen atoms (O)

CO2

Tright here is a various ascendancy for creating the chemical formula for each form of compound.

Ionic compounds are compounds in which positive metal ions and negative nonsteel ions are joined by ionic bonds. In these compounds, the chemical symbol for the positive steel ion is written first, adhered to by the symbol for the negative nonsteel ion. The video at the following URL gives a fuller explanation of ionic compounds and their formulas:http://www.youtube.com/watch?v=vscoYh6m46M.

· Q:The ionic compound lithium fluoride consists of a proportion of one lithium ion (Li+) to one fluoride ion (F-). What is the chemical formula for this compound?

· A:The chemical formula is LiF.

Covalent compounds are compounds in whichnonmetalsare joined by covalent bonds. In these compounds, the element that is farther to the left in the regular table is written initially, adhered to by the element that is farther to the ideal. If both elements are in the very same team of the periodic table, the one through the better duration number is composed first. The following URL offers a fuller explacountry of covalent compounds and also their formulas:http://www.youtube.com/watch?v=ZTMHbKtgI-M.

· Q:A molecule of the covalent compound nitrogen dioxide consists of one nitrogen atom (N) and also two oxygen atoms (O). What is the chemical formula for this compound?

· A:The chemical formula is NO2.

Summary

· Compounds are represented by chemical formulas. Elements in a compound are stood for by chemical symbols, and the ratio of different facets is represented by subscripts.

· There are various rules for writing the chemical formulas for ionic and covalent compounds.

Explore More

At the complying with URL, do the online discovering task on chemical formulas. Then take the quiz at the finish of the activity to check your comprehension.

http://www.wisc-online.com/Objects/ViewObject.aspx?ID=GCH603

Review

1. Complete the adhering to analogy: A chemical symbol is to an aspect as a chemical formula is to a(n) __________.

2. The compound sodium sulfide consists of a ratio of one sodium ion (Na+) to two sulfide ions (S2-). Write the chemical formula for this compound.

3. A molecule of sulfur dioxide consists of one sulhair atom (S) and two oxygen atoms (O). What is the chemical formula for this compound?

4. Identify the proportion of atoms in the compound represented by the following chemical formula: N2O5.

Ionic Compounds

Compounds in which electrons are moved from one atom to an additional.

· Describe ioniccompoundsand also exactly how they develop.

· Exordinary exactly how ioniccompoundsare named.

· Identify properties and provides of ioniccompounds.

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The truck pictured above is spanalysis crystals of the salt calcium chloride on a snowy road to prevent ice from developing. The crystals reduced thefreezingallude ofwaterso as soon as the snow melts, it won’t revolve to ice. Do you recognize why calcium chloride lowers the freezing allude of water? The answer hregarding do with the kind of compound that calcium chloride is. Calcium chloride is an ionic compound.

What Are Ionic Compounds?

All compounds create whenatomsof differentelementsshare or transferelectrons. Compounds in which electrons are transferred from one atom to an additional are called ioniccompounds. In this kind of compound,electronsactually relocate between theatoms, quite than being common in between them. When atoms give up or accept electrons in this way, they become charged pposts calledions. The ions are hosted together by ionic bonds, which develop an ionic compound. Ionic compounds generally create betweenelementsthat aremetalsand aspects that are nonsteels. For example, the steel calcium (Ca) and also the nonsteel chlorine (Cl) form the ionic compound calcium chloride (CaCl2). In this compound, tbelow are 2 negative chlorideionsfor each positive calcium ion. Because the positive and negative charges cancel out, an ionic compound is neutral in charge.

Q:Now have the right to you explain why calcium chloride avoids ice from developing on a snowy road?

A:If calcium chloride dissolves inwater, it breaks down right into itsions(Ca2+and also Cl-). Whenwaterhas actually ions liquified in it, it has actually a lowerfreezingsuggest. Pure water freezes at 0°C. With calcium and chloride ions liquified in it, it won’t freeze unmuch less thetemperaturereaches -29°C or reduced.

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Crystals

Many type of compounds develop molecules, yet ionic compounds form crystals instead. Acrystalconsists of many alternating positive and negative ions bonded together in a matrix. Look at the crystal of sodium chloride (NaCl) in theFigurelisted below. The sodium and also chloride ions are attracted to each other because they are oppositely charged, so they create ionic bonds.