Introduction to Atomic Mass and Molecular Mass
An atomic number is a total number of protons present in the nucleus of an atom. The mass of \(\frac{1}{12}\)th of an atom of the C12 isotope is called one atomic mass unit (1 amu) is called Atomic mass unit (AMU).
Summary
An atomic number is a total number of protons present in the nucleus of an atom. The mass of \(\frac{1}{12}\)th of an atom of the C12 isotope is called one atomic mass unit (1 amu) is called Atomic mass unit (AMU).
Things to Remember
- $$The\; actual\; mass\; of\; 1 \;amu=\frac{1}{12} \times \frac{12}{6.023\times10^{23}}$$
- $$No.\; of\; g\; mole = \frac{Mass\; in\; gram}{Molecular\; mass\; in\; g}$$
- $$No.\; of\; g\; mole = \frac{Mass\; in\; gram}{Molecular\; mass\; in\; g}$$
MCQs
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Subjective Questions
Q1:
Define meningitis .
Type: Very_short Difficulty: Easy
Show/Hide Answer
Answer: <p>Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The most common symptoms are fever, headache and neck stiffness. Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises.</p>
Q2:
Explain the different types of meningitis ?
Type: Long Difficulty: Easy
Show/Hide Answer
Answer: <p>Types</p>
<ul>
<li>Bacterial meningitis</li>
</ul>
<p>In premature babies and newborns up to three months old, common causes are group B streptococci (subtypes III which normally inhabit the vagina and are mainly a cause during the first week of life) and bacteria that normally inhabit the digestive tract such as Escherichia coli, Listeria monocytogenes is transmitted by the mother before birth and may cause meningitis in the newborn.</p>
<p>Older children are more commonly affected by Neisseria meningitides (meningococcus) and Streptococcus pneumoniae and those under five by Haemophilus influenzae type B (in countries that do not offer vaccination).</p>
<p> </p>
<ul>
<li>Tubercular meningitis</li>
</ul>
<p>Tuberculous meningitis, which is meningitis caused by Mycobacterium tuberculosis, is more common in people from countries in which tuberculosis is endemic, but is also encountered in persons with immune problems, such as AIDS.</p>
<p> </p>
<ul>
<li>Viral meningitis</li>
</ul>
<p>Viruses that cause meningitis include enteroviruses, herpes simplex virus (generally type 2, which produces most genital sores; less commonly type 1), varicella zoster virus (known for causing chickenpox and shingles), mumps virus, HIV, and LCMV. Mollaret's meningitis is a chronic recurrent form of herpes meningitis; it is thought to be caused by herpes simplex virus type 2.</p>
<p> </p>
<ul>
<li>Aseptic meningitis</li>
</ul>
<p>The term refers to all types of inflammation of the brain meninges which is not caused by pus caused by pus-forming bacteria. Viruses are the main cause and other non-infective factors may be responsible. It is a common inflammatory disorder of the meninges in children and adults.</p>
<p> </p>
<ul>
<li>Bacterial meningitis</li>
</ul>
<p>In premature babies and newborns up to three months old, common causes are group B streptococci (subtypes III which normally inhabit the vagina and are mainly a cause during the first week of life) and bacteria that normally inhabit the digestive tract such as Escherichia coli, Listeria monocytogenes is transmitted by the mother before birth and may cause meningitis in the newborn.</p>
<p>Older children are more commonly affected by Neisseria meningitides (meningococcus) and Streptococcus pneumoniae and those under five by Haemophilus influenzae type B (in countries that do not offer vaccination).</p>
<p> </p>
<ul>
<li>Tubercular meningitis</li>
</ul>
<p>Tuberculous meningitis, which is meningitis caused by Mycobacterium tuberculosis, is more common in people from countries in which tuberculosis is endemic, but is also encountered in persons with immune problems, such as AIDS.</p>
<p> </p>
<ul>
<li>Viral meningitis</li>
</ul>
<p>Viruses that cause meningitis include enteroviruses, herpes simplex virus (generally type 2, which produces most genital sores; less commonly type 1), varicella zoster virus (known for causing chickenpox and shingles), mumps virus, HIV, and LCMV. Mollaret's meningitis is a chronic recurrent form of herpes meningitis; it is thought to be caused by herpes simplex virus type 2.</p>
<p> </p>
<ul>
<li>Aseptic meningitis</li>
</ul>
<p>The term refers to all types of inflammation of the brain meninges which is not caused by pus caused by pus-forming bacteria. Viruses are the main cause and other non-infective factors may be responsible. It is a common inflammatory disorder of the meninges in children and adults.</p>
<p> </p>
Q3:
Write the nursing management of meningits ?
Type: Short Difficulty: Easy
Show/Hide Answer
Answer: <p>Nursing management</p>
<ul>
<li>Careful monitoring of temperature, vital signs, circulatory status.</li>
<li>Check for neurological signs and monitor</li>
<li>Assess the level of consciousness</li>
<li>Signs of increased ICP</li>
<li>Glasgow coma scale</li>
<li>Measure head circumference</li>
</ul>
<p> </p>
<ul>
<li>Assess neurologic status and vital signs constantly. Determine oxygenation from arterial blood gas values and pulse oximetry.</li>
<li>Insert cuffed endotracheal tube (or tracheostomy), and post-position patient on mechanical ventilation as prescribed.</li>
<li>Assess blood pressure (usually monitored using an arterial line) for incipient shock, which precedes cardiac or respiratory failure.</li>
<li>Rapid IV fluid replacement may be prescribed, but take care not to overhydrate patient because of a risk of cerebral edema.</li>
<li>Reduce high fever to decrease the load on heart and brain from oxygen demands.</li>
<li>Protect the patient from injury secondary to seizure activity or altered a level of consciousness (LOC).</li>
<li>Monitor daily body weight; serum electrolytes; and urine volume, specific gravity, and osmolality, especially if syndrome of inappropriate antidiuretic hormone (SIADH) is suspected.</li>
<li>Prevent complications associated with immobility, such as pressure ulcers and pneumonia.</li>
<li>Institute infection control precautions until 24 hours after initiation of antibiotic therapy (oral and nasal discharge is considered infectious).</li>
<li>Inform family about patient’s condition and permit a family to see a patient at appropriate intervals.</li>
</ul>
<p> </p>
<ul>
<li>Careful monitoring of temperature, vital signs, circulatory status.</li>
<li>Check for neurological signs and monitor</li>
<li>Assess the level of consciousness</li>
<li>Signs of increased ICP</li>
<li>Glasgow coma scale</li>
<li>Measure head circumference</li>
</ul>
<p> </p>
<ul>
<li>Assess neurologic status and vital signs constantly. Determine oxygenation from arterial blood gas values and pulse oximetry.</li>
<li>Insert cuffed endotracheal tube (or tracheostomy), and post-position patient on mechanical ventilation as prescribed.</li>
<li>Assess blood pressure (usually monitored using an arterial line) for incipient shock, which precedes cardiac or respiratory failure.</li>
<li>Rapid IV fluid replacement may be prescribed, but take care not to overhydrate patient because of a risk of cerebral edema.</li>
<li>Reduce high fever to decrease the load on heart and brain from oxygen demands.</li>
<li>Protect the patient from injury secondary to seizure activity or altered a level of consciousness (LOC).</li>
<li>Monitor daily body weight; serum electrolytes; and urine volume, specific gravity, and osmolality, especially if syndrome of inappropriate antidiuretic hormone (SIADH) is suspected.</li>
<li>Prevent complications associated with immobility, such as pressure ulcers and pneumonia.</li>
<li>Institute infection control precautions until 24 hours after initiation of antibiotic therapy (oral and nasal discharge is considered infectious).</li>
<li>Inform family about patient’s condition and permit a family to see a patient at appropriate intervals.</li>
</ul>
<p> </p>
Q4:
How can we diagnose meningitis ?
Type: Short Difficulty: Easy
Show/Hide Answer
Answer: <ul>
<li>History and physical examination</li>
<li>LP and cerebrospinal fluid (CSF) analysis</li>
<li>CBC count</li>
<li>Blood culture and sensitivity test</li>
<li>CT scan</li>
<li>MRI</li>
</ul>
<p> </p>
<li>History and physical examination</li>
<li>LP and cerebrospinal fluid (CSF) analysis</li>
<li>CBC count</li>
<li>Blood culture and sensitivity test</li>
<li>CT scan</li>
<li>MRI</li>
</ul>
<p> </p>
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Introduction to Atomic Mass and Molecular Mass
Atomic Mass and Molecular Mass
Some of The terms related to atom and molecule are introduced just in brief so that they might help to solve chemical arithmetic smoothly.
- Atomic number: It is a total number of protons present in the nucleus of an atom e.g. carbon atom contains 6 protons; its atomic number is 6.
Atomic number is also the number of electrons present in the neutral atom. - Atomic mass number: It is the total number of protons and neutrons present in an atom of an element e.g. carbon contains 6 protons and 6 neutrons.
Therefore, \(\begin{align*}\text{the atomic mass number of carbon}&=No.\; of\; protons + No.\; of\; neutrons\;\\ &=6+6\\&=12\\ \end{align*}\)
A proton and a neutron have identical mass, so they are commonly called as nucleon. It means carbon contains twelve nucleons. Symbolically, the atomic number and atomic mass number of carbon are denoted as 12C6. - Isotopes: Different species of an element having the same atomic number and different atomic mass number are called isotopes. Isotopes are chemically identical but differ in their physical properties such as melting point, boiling point, density etc.
Isotopes of an element arise by the difference of the number of neutrons. Most of the elements have at least two isotopes e.g. H consists of three isotopes. Those are protium (1H1), deuterium(2H1) and tritium (3H1). The first two are stable isotopes but the third one is the radioactive isotope. - Isobars: They are the species having a different atomic number but the same atomic mass number.
e.g. 24Na11 and 24Mg12 called isobars. - Atomic mass unit (AMU): The mass of \(\frac{1}{12}\)th of an atom of C12isotope is called one atomic mass unit (1 amu). The mass of all atoms and molecules are expressed with reference to the mass of one amu.
$$The\; actual\; mass\; of\; 1 \;amu=\frac{1}{12} \times \frac{12}{6.023\times10^{23}}$$
=1.66\(\times\)10-24g - Average atomic mass (Atomic weight): It is defined as the average mass of an element with respect to the mass of \(\frac{1}{12}\)the of an atom of the C-12 isotope.
The average of an isotopic mass of all the isotopes present in the natural mixture is the atomic mass of an element.
Mathematically,
$$Atomic\; mass = \frac{Mass\; of\; 1 \;atom \;of\; the\; element}{\frac{1}{12} of \;mass \;of \;1\; atom\; of C^{12}}$$
$$= \frac{Mass\; of\; 1\; atom\; of\; the\; element}{Mass\; of\; 1\; atom\; of\; C^{12}}\times\;12$$
Atomic mass begins an average mass, it is fractional in number e.g. Two isotopes of chlorine have atomic masses 35 and 37 and are present in chlorine in the ratio of 3:1 respectively. The average relative weight of chlorine, therefore, would be = \(\frac{35\times3+37}{4}\) =35.5 or \(\frac{35\times\;75\;+\;37\;\times\;25}{100}\) = 35.5 amu
Hence, the fractional atomic mass of an element is due to the presence of different isotopes in natural mixture with a different percentage. - Gram-atom (Gram atomic mass): Atomic weight is simply a number, which does not have any unit of mass. The gram atomic weight or simply gram atom is the atomic weight expressed in terms of grams. Therefore, 1 gram atom of hydrogen weighs 1 gram. Similarly one gram atom of oxygen, sulphur and sodium weigh 16 g, 32 g, and 23 g respectively. Hydrogen and oxygen are molecular species. Their molecules are diatomic whereas carbon and sodium are atomic species. The molecules of carbon and sodium are monatomic. Therefore, when we say one gram molecule or gram mole of hydrogen, it is 2 g of hydrogen and one gram mole of oxygen means 32g of oxygen. Similarly one gram-mole of carbon dioxide is 44 gram (CO2 = 12+16\( \times\) 2=44).
$$No.\; of\;gram\; atom\; of \;element =\left(\frac{Mass\; of\; element\; in\; gram}{Atomic\; mass\; of\; element}\right)$$ - Molecular Mass or Molecular Weight: It is the mass of a molecule of a substance with respect to the mass of \(\frac{1}{12}\)thof an atom of C-12 isotope e.g. the molecular masses of H2O, CO2 and NaCl are 18, 44 and 58.5 amu respectively.
A molecular mass is calculated by the summation of atomic masses of all the atoms present in the given molecule e.g. molecular mass of C6H12O6 = 6*12+12*1+6*16 = 180 amu. - Gram Molecular Mass (g mole): The molecular mass is a relative term and it is a unitless number e.g. molecular mass of H2SO4 = 98. It means, the weight of 1 molecule of H2SO4 is 98 times heavier than the mass of \(\frac{1}{12}\)th of an atom of C-12 isotope (i.e. 1 amu). When the molecular mass of a substance is expressed in gram, it is called one gram molecular mass or 1 g mole.
For example:
Molecular mass of H2 = 2 amu and 2 g of H2 = 1 g mole of H2
Molecular mass of CO2 = 44 amu and 44 g of CO2 = 1 g mole of CO2
Mathematically, we have
$$No.\; of\; g\; mole = \frac{Mass\; in\; gram}{Molecular\; mass\; in\; g}$$
Bibliography
Pant, Manju, Bhoj Raj Bhattarai and Nab Raj Adhikari. Comprehensive Chemistry. 6th edition . Vol. 1 . Kathmandu: Heritage Publisher and Distributors Pvt. Ltd., 2072.
Lesson
Atomic Mass and Molecular Mass
Subject
Chemistry
Grade
Grade 11
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