Br Atom

Posted : admin On 1/3/2022
  • First, Br 2 molecule is polarized by alkene bond. With that, electrons in the double bond attacks the positively charged Br atom and forms a cyclic bromonium ion. Other Bromine atom is eliminated as a bromide ion.
  • Substitution reaction, any of a class of chemical reactions in which an atom, ion, or group of atoms or ions in a molecule is replaced by another atom, ion, or group. An example is the reaction in which the chlorine atom in the chloromethane molecule is displaced by the hydroxide ion, forming.

The isolated K atom is larger than the isolated Br atom. What type of bond is expected between K and Br? Which Ion in the compound KBr is larger? K is the largest ion in the compound KBr (2) Define: Bond length and Bond energy.

Chapter 13: Spectroscopy

Isotope patterns for -Cl and -Br

Br atom model
  • Mass spectrometers are capable of separating and detecting individual ions even those that differ only by a single atomic mass unit (note in rality they are far more sensitive than that!)
  • As a result, molecules containing different isotopes can be distinguished.
  • This is most apparent (at this level) when atoms such as bromine or chlorine are present in a molecule because those elements naturally exist with a significant % of the heavier isotope.
  • For example, while C has 2 common isotopes, 12C and 13C, 13C represents only about 1% of natural carbon. In contrast, Cl has 2 common isotopes, 35Cl and 37Cl, with about 25% being 37Cl.
  • Typically, one looks at the molecular ion peak, 'M' (since this is being identified and used to determine the MW).
  • When working with MW from the molecular ion in MS, the best approach is to always use the lighter ion (i.e. M) and the mass of the lighter isotope (i.e. for Cl use 35 not 35.5, or, for Br use 79 and not 80)
  • 35Cl : 37Cl exists naturally in an almost 3:1 ratio, so we observe peaks at 'M' (molecules with an atom of 35Cl) and 'M+2' (molecules an atom of 37Cl) are obtained with relative intensity 3:1
  • 79Br : 81Br exists naturally in an almost 1:1 ratio, so we observe peaks at 'M' (molecules with an atom of 79Br) and 'M+2' (molecules an atom of 81Br) are obtained with relative intensity 1:1
  • Note that since the relative natural abundances of the isotopes are different, you can tell the difference between the presence of Cl and Br. The patterns are different, they look different.
  • 'M+1' peaks are usually seen due to the presence of 13C in the sample but because 13C is only about 1% of natural carbon, the peaks tend to be small (unless there is a large number of C atoms present). Note that you can see the small peaks due to the presence of 13C in the figures shown for Cl and Br, they look like little shadows on the right of the other peaks.

The following two examples of mono-haloalkanes mass spectra show the characteristic isotope patterns of monohalogenated molecules. The patterns are highlighted in the green boxes:

Example 1 :

This MS is of 2-chloropropane, C3H7Cl.

Note the characteristic isotope pattern at 78 (M) and 80 (M+2) in a 3:1 ratio.
Loss of 35Cl from 78 or37Cl from 80 gives the base peak a m/z = 43 (M - 35 = M+2 - 37 = 43) corresponding to the secondary propyl cation.
Note that the peaks at m/z = 63 and 65 represent fragment ions that still contain Cl and therefore also show the 3:1 isotope pattern.
The very small peak at 79 represents M+1, the small number of molecules that contain 35Cl and an atom of 13C rather than 12C.
The even smaller peak at 81 presents M+2+1 = M+3, a very small number of molecules that contain 37Cl and an atom of 13C rather than 12C.

Example 2 :

This MS is of 1-bromopropane, C3H7Br.

Note the isotope pattern at 122 and 124 represents the M and M+2 in a 1:1 ratio.
Loss of 79Br from 122 or 81Br from 124 gives the base peak a m/z = 43, corresponding to the propyl cation.
Note that other peaks, such as those at m/z = 107 and 109 (yes, they are small) still contain Br and therefore still show the 1:1 isotope pattern.

Note: the isotope patterns for polyhalogenated molecules (such as having both -Cl and -Br or with multiple -Cl or -Br) give different (but still characteristic isotope patterns).

© Dr. Ian Hunt, Department of Chemistry

The HTML <br> element produces a line break in text (carriage-return). It is useful for writing a poem or an address, where the division of lines is significant.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone and send us a pull request.

As you can see from the above example, a <br> element is included at each point where we want the text to break. The text after the <br> begins again at the start of the next line of the text block.

Note: Do not use <br> to create margins between paragraphs; wrap them in <p> elements and use the CSSmargin property to control their size.


Br Atom

This element's attributes include the global attributes.

Deprecated attributes

Indicates where to begin the next line after the break.

Styling with CSS

The <br> element has a single, well-defined purpose — to create a line break in a block of text. As such, it has no dimensions or visual output of its own, and there is very little you can do to style it.


You can set a margin on <br> elements themselves to increase the spacing between the lines of text in the block, but this is a bad practice — you should use the line-height property that was designed for that purpose.


Simple br

In the following example we use <br> elements to create line breaks between the different lines of a postal address:


The result looks like so:

Accessibility concerns

Creating separate paragraphs of text using <br> is not only bad practice, it is problematic for people who navigate with the aid of screen reading technology. Screen readers may announce the presence of the element, but not any content contained within <br>s. This can be a confusing and frustrating experience for the person using the screen reader.

Use <p> elements, and use CSS properties like margin to control their spacing.

Technical summary

Content categoriesFlow content, phrasing content.
Permitted contentNone, it is an empty element.
Tag omissionMust have a start tag, and must not have an end tag. In XHTML documents, write this element as <br />.
Permitted parentsAny element that accepts phrasing content.
Implicit ARIA roleNo corresponding role
Permitted ARIA rolesnone, presentation
DOM interfaceHTMLBRElement

Br Atomic Symbol


HTML Living Standard
The definition of '<br>' in that specification.
Living Standard
The definition of '<br>' in that specification.
HTML 4.01 Specification
The definition of '<br>' in that specification.

Browser compatibility

BCD tables only load in the browser

Br Atom Charge

See also

Br Atom

  • <address> element
  • <p> element
  • <wbr> element