Atoms and Atomic Structure

To determine the atomic number of an element with a mass number of 22, you would need the number of protons in the nucleus. Since the mass number is the sum of protons and neutrons, subtracting the number of neutrons (mass number) from the mass number gives you the number of protons (atomic number).

The number of electrons emitted when calcium is flashed with light of a certain wavelength and intensity depends on the photoelectric effect, which is related to the energy of the photons hitting the metal. Without the energy of the photons and the work function of calcium, we cannot determine the number of electrons emitted.

let's start with what a mole is...

think of "a dozen".. what is that? 12 right?

a dozen = 12 of anything.. 12 donuts. 12 people, 12 answers to this question.. agreed?

A pair = 2 of anything...a pair of aces = 2 aces. Pair of shoes = 2 shoes. Pair of contact lenses = 2 lenses. etc.. pair = 2

a gross = 144 of anything.... right?

bakers dozen = 13..... 13 cookies = a bakers dozen

dozen, pair,gross and bakers dozen are all "labels" we give to a quantity of something.... right?

a "mole" is just like dozen, pair, and gross etc. it is a label we give to a quantity of something. The number, though, is = 602,200,000,000,000,000,000,000... we usually write that as 6.022x10^23

a mole of donuts = 6.022x10^23 donuts

a mole of answers = 6.022x10^23 answers. take awhile to read all those...

a mole of people = 6.022x10^23 people...

a mole of 1 dollar bills = $6.022x10^23

and just like

2 dozen donuts = 2 x 12 donuts = 24 donuts

2 moles of donuts = 2 x 6.022x10^23 donuts = 1.204x10^24 donuts

got that down? Nothing mysterious. just a label. just like a dozen

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now that you know what it is, how do we use it?

First, we have a "mole" because the number of atoms of stuff that we can hold in our hand and see is HUGE. That is because atoms are tiny. In the lab, we would probably work with say a gram of something. probably about the size of a couple of aspirin. depending on the substance, that's probably about 1/10th of a mole = 6.022x10^22 atoms. so it's a convenient unit of measure. Rather than saying 60,220,000,000,000,000,000,000 atoms, we say 0.1 moles... ok?

Next, the atomic masses listed on a periodic table are in units called "AMU's".. atomic mass units. and can be read as AMU per atom.

but 1 amu = 1.66x10^-24 g

and there are 6.022x10^23 atoms in 1 mole of atoms right? that's what a mole is

now see if you can follow...

(1 amu / atom) x (6.022x10^23 atoms / mole) x (1.66x10^-24 g / amu) = 1g / mole of atoms...usually just written g/mole

notice what I've done? I've converted amu/atom to g/mole.. units of amu / amu cancel... atoms / atom cancel and we're left with g/mole

What that gibberish means is this. You can read atomic mass on a periodic table as either amu/atom or g/mole... They are equivalent units.

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Next.

now that you have atomic mass in grams / mole what does that mean?

for carbon 12, for example, atomic mass = 12.01 g / mole. that means if you have 12.01 g, you have 1 mole of Carbon 12. ie 6.022x10^23 atoms of carbon 12

if you have 3.01x10^23 atoms of carbon 12, you have 1/2 of a mole. since 1 mole weighs 12.01 g, you have 6.00 grams of Carbon..

See how that works?

let's try a couple of practice problems

a)

calculate moles of C in 24.02 g C

from the periodic table, the atomic mass of C = 12.01 amu/atom = 12.01 g/mole right?

24.02 g C x (1 mole C / 12.01 g C) = 2.000 moles C... g/g cancels..

b)

calculate mass of C in 3.00 moles C

3.00 moles C x (12.01 g C / mole C) = 36.03 g C... moles / moles cancel

c)

calculate moles NaCl in 116.8 g NaCl...

from periodic table mass Na = 23.0 g mass Cl = 35.4... so mass NaCl = 1x23 + 1x35.4 = 58.4 g/mole

116.8 g NaCl x (1 mole NaCl / 58.4 g) = 2.00 moles NaCl.. g/g cancels... leaves moles.. do you see that?

d)

how many atoms are in 2 moles of C?

2 moles x (6.022x10^23 atoms C / mole C) = 1.204x10^24 atoms

NOTE: this takes practice. which is why you get assignments to do these conversions. Ok? practice.

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when you start working in the lab and start working problems with chemical equations, moles are important. this is why...

the coefficients of balanced chemical equations are mole ratios. not mass...

2 H2 + 1 O2 ---> 2 H2O... the 2,1,and 2 are MOLES (or you could read it as molecules also)

2 moles H2 reacts with 1 mole O2..ok?

it ISN'T,2 grams of H2 reacts with 1 gram O2 to form 2 grams of H2O.

so we convert masses to moles to use the balanced equations to calculate how much reactants we need and products we produce.

whew...

ask questions if you need to.. I'll check back in the morning.

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as to the actual definition, a mole is technically defined as "the number of elemental entities in 12 g of carbon 12" = 6.022x10^23.

An equivalent to Shell Alvania 2 grease would be a general-purpose lithium-based grease with a similar consistency and application range. Some common alternatives include Mobilgrease 28, Chevron Multifak EP 2, and Exxon Centaur Moly.

The balanced nuclear equation for the alpha decay of thorium-230 is:

^230Th → ^226Ra + ^4He

there are two lone pairs on the oxygen of water but because of the orbital geometry, only one lone pair can have the correct orientation to make a bond and the other lone pair pointing away from the central atom, therefor water is monodentate not bidentate. and for bidentate ligands require distint lone pairs on distinct atoms.

A Ali Sudais jan

Nuclear medicine

Research Scholar

Centre for Nuclear and molecular studies

Plants and animals do not have positive and negative charges in the same way that inanimate objects do. However, living organisms do have electrical activity in the form of nerve impulses and muscle contractions, which involve movement of ions. These electrical activities are essential for various biological functions.

Non-metal ions typically have a charge that corresponds to the number of electrons they need to gain to achieve a stable electron configuration, usually by gaining enough electrons to fill their outermost energy level. For example, elements in Group 15 usually gain three electrons to form ions with a 3- charge, while those in Group 17 usually gain one electron to form ions with a 1- charge.

An atom (as from the Periodic Table, which have no charge) will have the same amount of protons as electrons.

The atomic number is the amount of protons an atom has. Lithium has an atomic number of 3, which means it's nucleus contains 3 protons, and in turn 3 electrons.

Once you identify the atom based on it's atomic number, and find it on the periodic table, you can see it's symbol, and weight.

The atomic weight is the amount of protons and neutrons added together, both weighing 1 amu (*atomic mass units*: The unit that protons and neutrons are measured). Lithium has an atomic weight of 6.94, so the amount of protons (3) subtracted from 6.94 is 3.94. Now we round up to the nearest whole number and we have 4. Four is the amount of neutrons an atom of Lithium has.

Neutron number is not conserved in radioactive decay processes. During beta decay, a neutron may convert into a proton, an electron (beta particle), and an antineutrino. This results in a change in neutron number.

Wham Shell is a character from the Skylanders video game series, released in 2012. The character is already available for play in the game. If you are referring to a different release or game, please provide more context for a more accurate answer.

Non-metals gain electrons from metals because non-metals have a higher electronegativity, which means they have a stronger pull on electrons. Metals tend to lose electrons easily due to their low electronegativity, making them more likely to transfer electrons to non-metals in ionic bonding to achieve stable electron configurations.

No, 1 mole of NaCl will produce 2 ions (1 Na+ and 1 Cl-) while 1 mole of MgCl2 will produce 3 ions (1 Mg2+ and 2 Cl-), so they do not have an equal number of ions.

Noble gases are non polar like all other elements.

An element consists of identical atoms, each having the same number of protons in its nucleus. These atoms are characterized by a specific atomic number on the periodic table.

This is not a question or a sentance for that mater. Please restructure. Hydrogen is the smallest pure element. Smallest main structure component of an element is the electron. Hope this helped.

A person who has an idea to share is often called a visionary, innovator, or thought leader.

The correct equation for the alpha decay of Polonium-214 is:
218/84Po -> 214/82Pb + 4/2He
This shows the decay of Polonium-214 into Lead-214 and a Helium nucleus, where the atomic number and mass numbers are conserved.

Yes, nitrogen, oxygen, and hydrogen can all exist together in a mixture of liquids. These gases can dissolve in liquids to varying degrees depending on factors like temperature and pressure. For example, nitrogen and oxygen are more soluble in water compared to hydrogen.

Thorium 230 has 90 electrons and 140 neutrons.

The potential energy in the system made up by the two charges will decrease. Of course, this energy doesn't just disappear, it has to go somewhere. For example, useful work may be done, or the energy may be dissipated as heat, sound, electromagnetic waves, etc.

Protons are composite particles made of quarks held together by strong nuclear forces, while electrons are fundamental particles with spin. The spin of a proton is due to the motion of its quarks, rather than an intrinsic property like the spin of an electron.

Barium 137 has 56 protons and 56 electrons.

The charge of an atom may be unbalanced, refering to the levels of electrons, which are inmeasurable in speed, and are nearly impossible to detect when they conduct from one atom to another, which bonds the atoms together into crystal. When electrons move from crystal to crystal, the crystals pull together to form crystal lattice, the base brick of known matter.

When an atom gains a positive charge, it loses one or more electrons. This alters its charge but not its identity as an element. The number of protons, which defines the element, remains the same in a positively charged atom.