What Is The Overall Charge Of An Atom?
- 1 Why do ions have an overall charge?
- 2 How is the charge (-) or (+) assigned to the ion?
- 3 Why is the overall charge of the atom neutral or zero?
- 4 Is overall positively charged according to the protons?
- 5 What is it called when the overall charge becomes positive?
- 6 Is an ion always negative?
What is the overall charge of an ion?
Anions and cations – “Anion” redirects here. Not to be confused with the quasiparticle Anyon, Hydrogen atom (center) contains a single proton and a single electron, Removal of the electron gives a cation (left), whereas the addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation,
- Hydrogen forms the only charge-+1 cation that has no electrons, but even cations that (unlike hydrogen) retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.
- Anion (−) and cation (+) indicate the net electric charge on an ion.
- An ion that has more electrons than protons, giving it a net negative charge, is named an anion, and a minus indication “Anion (−)” indicates the negative charge.
With a cation it is just the opposite: it has less electrons than protons, giving it a net positive charge, hence the indication “Cation (+)”. Since the electric charge on a proton is equal in magnitude to the charge on an electron, the net electric charge on an ion is equal to the number of protons in the ion minus the number of electrons.
- An anion (−) ( ANN -eye-ən, from the Greek word ἄνω ( ánō ), meaning “up” ) is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).
- A cation (+) ( KAT -eye-ən, from the Greek word κάτω ( káto ), meaning “down” ) is an ion with fewer electrons than protons, giving it a positive charge.
There are additional names used for ions with multiple charges. For example, an ion with a −2 charge is known as a dianion and an ion with a +2 charge is known as a dication, A zwitterion is a neutral molecule with positive and negative charges at different locations within that molecule.
How do we find the overall charge of a compound?
Learning Objectives –
Write the chemical formula for a simple ionic compound based on the charges of the cations and anions in the compound.
In every ionic compound, the total number of positive charges of the cations equals the total number of negative charges of the anions. Thus, ionic compounds are electrically neutral overall, even though they contain positive and negative ions. We can use this observation to help us write the formula of an ionic compound.
Why do ions have an overall charge?
An ion is a charged particle formed when an atom or molecule loses or gains electrons from the outer shells, causing the number of protons and electrons to become unequal. Protons are positively charged and electrons are negatively charged. If the atom or molecule has lost electrons, the number of protons is greater than the number of electrons.
Therefore, the number of positive charges is greater than the number of negative charges and the particle becomes positively charged overall. If the atom or molecule has gained electrons, the number of electrons is greater than the number of protons. Therefore, the number of negative charges is greater than the number of positive charges and the particle becomes negatively charged overall.
There is always a force of attraction between two oppositely charged ions. This is because of the basic principle of ‘opposites attract’, where any two objects with opposing electrical charges are attracted towards each other. The force of attraction between oppositely charged ions causes them to form an ionic compound.
Is an ion with an overall positive charge?
What is a cation ? – A cation is an ion with positive charge, which means it has more protons (positively-charged particles) than electrons (negatively-charged particles). Cations are formed when an atom loses one or more electrons: the loss of the negatively-charged electron(s) results in an overall positive charge.
How is the charge (-) or (+) assigned to the ion?
Learning Objectives –
- To describe the characteristics of ionic bonding.
- To quantitatively describe the energetic factors involved in the formation of an ionic bond.
Ions are atoms or molecules which are electrically charged. Cations are positively charged and anions carry a negative charge. Ions form when atoms gain or lose electrons. Since electrons are negatively charged, an atom that loses one or more electrons will become positively charged; an atom that gains one or more electrons becomes negatively charged.
- Ionic bonding is the attraction between positively- and negatively-charged ions.
- These oppositely charged ions attract each other to form ionic networks (or lattices ).
- Electrostatics explains why this happens: opposite charges attract and like charges repel.
- When many ions attract each other, they form large, ordered, crystal lattices in which each ion is surrounded by ions of the opposite charge.
Generally, when metals react with non-metals, electrons are transferred from the metals to the non-metals. The metals form positively-charged ions and the non-metals form negatively-charged ions.
Do ions have no overall charge?
IC. Ionic Compounds IC2. Counterions Compounds are mixtures of elements bonded together to make one material. Compounds can contain two or more elements. Those elements have to be found in a specific ratio. Two materials that contain the same two elements bonded together, but in different ratios, are two different compounds.
Two materials that contain two different pairs of elements bonded together, but in the same ratio, would still be different compounds. In nature, elements are found bound up in compounds more often than not. One common way for elements to be bound together is to form a salt. Salts are found very frequently in the earth’s crust.
A salt contains both anions and cations. Cations are not generally found alone. Anions are not generally found alone. They need counterions to balance out their charges. Imagine two atoms get together to form a salt. A sodium atom comes together with a fluorine atom.
Anions and cations are always found together. The charges on the cations must balance the charges on the anions.
For example, sodium chloride is a very common ionic compound. It is the main component of table salt, used in cooking. Sodium chloride contains sodium ions, each with a +1 charge, and chloride ions, each with a -1 charge. Overall, the compound has no charge, because the positive sodiums balance out the charge on the negative chlorides, and vice versa.
Na + + Cl – = NaCl (no overall charge) (equation IC2.1) In a similar way, other ionic compounds form so that there is no overall charge on the compound. Magnesium oxide forms in a ratio so that the positive charges on the magnesium balance the negative charges on the oxygen. Mg 2+ + O 2- = MgO (no overall charge) (equation IC2.2) However, sodium oxide would need to form in a different ratio in order to keep the positive and negative charges balanced.
Instead of forming in a one-to-one ratio, there would need to be double the number of sodium ions as oxygen ions in order to have the charges cancel each other exactly.2 Na + + O 2- = Na 2 O (no overall charge) (equation IC2.3) The two positive charges on the two sodium cations balance out the two negative charges on the oxide anion.
- Problem IC2.1.
- What would be the ratio of elements if each of the following ions formed a salt with chloride ions, Cl – ? a) K + b) Fe 3+ c) Mo 6+ d) Zr 4+ Problem IC2.2.
- What would be the ratio of elements if each of the following ions formed a salt with oxide ions, O 2- ? a) Li + b) Fe 3+ c) Cr 6+ d) Ti 4+ Problem IC2.3.
What would be the ratio of elements if each of the following ions formed a salt with nitride ions, N 3- ? a) Li + b) Ta 3+ c) W 6+ d) Co 2+ Problem IC2.4. Some compounds are more complicated. In the following polyoxoanions, the metal and oxide charges do not quite cancel.
- Given the charge on the metal, and assuming oxide has a 2- charge, what would be the overall charge on the polyoxoanion? Suggest the right ratio of counterion(s) that could balance the charge in each case (e.g.3 Li + ions, etc).
- A) WO 4 n- (W 6+ ) b) V 4 O 12 n- (V 5+ ) c) Mo 4 O 14 n- (Mo 6+ ) d) Cr(OH) 6 Mo 6 O 18 n- (OH -, Cr 4+, Mo 6+ ) Ionic compounds have no overall charge.
Instead, they consist of anions and cations found together to balance charge. The number of positive charges in an ionic compound equal the number of negative charges. Overall, the charge is balanced out. Why does the charge need to be balanced out? Imagine a bottle of sodium cations.
- There are a few problems with the cations in that bottle.
- First of all, the cations will all repel each other.
- You’d better stand back when you take the lid off.
- The repulsion between the sodium atoms will make them erupt out of the bottle like a volcano.
- By the way, what happened to all of the electrons when somebody made that bottle of sodium ions? Did they also make a jar of electrons with the leftovers? Did the two bottles sit on their shelves in a factory in Milwaukee until someone in Cleveland ordered a bottle of sodium ions and somebody in Tampa ordered a bottle of electrons? The problem with that story lies in Coulomb’s law, the mathematical relationship that talks about the force of attraction between two charges.
A transformation of Coulomb’s law deals with the energy needed to separate opposite charges. It would take a lot of energy to separate a whole bottle of electrons from a whole bottle of sodium cations, and even more energy to send one bottle to Cleveland and another to Tampa.
- You would need a power station to generate a bazillion gigawatts of energy to get the job done.
- On the other hand, people really can generate cations or anions in instruments such as mass spectrometers.
- They can even keep those ions for a while in “ion traps”.
- They would only do this with extremely small numbers of ions, though (nowhere near a visible amount), and it does take a generous amount of power.
Once they switch the mass spectrometer off, the ions won’t stick around for long. This site was written by Chris P. Schaller, Ph.D., College of Saint Benedict / Saint John’s University (retired) with contributions from other authors as noted. It is freely available for educational use. Structure & Reactivity in Organic, Biological and Inorganic Chemistry by Chris Schaller is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License, Send corrections to [email protected] Navigation: Back to Ionic Compounds Index Back to Structure & Reactivity Web Materials
Why is the overall charge negative?
16.2 Two kinds of charge (ESAER) – All objects surrounding us (including people!) contain large amounts of electric charge. There are two types of electric charge: positive charge and negative charge. If the same amounts of negative and positive charge are found in an object, there is no net charge and the object is electrically neutral, Positive charge is carried by the protons in material and negative charge by electrons. The overall charge of an object is usually due to changes in the number of electrons. To make an object:
- Positively charged : electrons are removed making the object electron deficient,
- Negatively charged : electrons are added giving the object an excess of electrons.
So in practise what happens is that the number of positive charges (protons) remains the same and the number of electrons changes:
Why is the overall charge of the atom neutral or zero?
Electrons are negatively charged species and protons are positively charged species. Atoms have equal number of electrons and protons with a net charge equal to zero. This makes atoms always neutral.
Is an ion always positive?
An ion is a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule. An atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom. : Propulsion
Is overall positively charged according to the protons?
Electrons – Electrons are one of three main types of particles that make up atoms. Unlike protons and neutrons, which consist of smaller, simpler particles, electrons are fundamental particles that do not consist of smaller particles. They are a type of fundamental particle called leptons.
All leptons have an electric charge of \(-1\) or \(0\). Electrons are extremely small. The mass of an electron is only about 1/2000 the mass of a proton or neutron, so electrons contribute virtually nothing to the total mass of an atom. Electrons have an electric charge of \(-1\), which is equal but opposite to the charge of a proton, which is \(+1\).
All atoms have the same number of electrons as protons, so the positive and negative charges “cancel out”, making atoms electrically neutral. Unlike protons and neutrons, which are located inside the nucleus at the center of the atom, electrons are found outside the nucleus.
Because opposite electric charges attract one another, negative electrons are attracted to the positive nucleus. This force of attraction keeps electrons constantly moving through the otherwise empty space around the nucleus. The figure below is a common way to represent the structure of an atom. It shows the electron as a particle orbiting the nucleus, similar to the way that planets orbit the sun.
However, this is an incorrect perspective, as quantum mechanics demonstrates that electrons are more complicated. Figure \(\PageIndex \): Electrons are much smaller than protons or neutrons. If an electron was the mass of a penny, a proton or a neutron would have the mass of a large bowling ball!
What is it called when the overall charge becomes positive?
Ions – As introduced previously, atoms contain a nucleus with neutrons and positively charged protons, surrounded by negatively charged electrons. In an atom, the total number of electrons, negative charge, equals the total number of protons, positive charge, and therefore, atoms are electrically neutral or uncharged.
- If an atom loses or gains electrons, it will become a positively or negatively charged particle, called an ion,
- The loss of one or more electrons results in more protons than electrons and an overall positively charged ion, called a cation,
- For example, a sodium atom with one less electron is a cation, Na +, with a +1 charge (Figure \(\PageIndex \)).
Figure \(\PageIndex \): A sodium atom (Na) has equal numbers of protons and electrons (11) and is uncharged. When it loses an electron, the resulting sodium cation has one more proton (11) than electrons (10), giving it an overall positive one charge, Na+.
When an atom gains one or more electrons, it becomes a negatively charged a nion, because there are more electrons than protons. When chlorine gains one electron it forms a chloride ion, Cl –, with a –1 charge (Figures \(\PageIndex \)) The names for positive and negative ions are pronounced CAT-eye-ons (cations) and ANN-eye-ons (anions), respectively.
Figure \(\PageIndex \): A chlorine atom (Cl) has equal numbers of protons and electrons (17) and is uncharged. When it gains an electron, the resulting chlorine anion has one more electron (18) than protons (17), giving it an overall negative one charge, Cl–.
Is every atom an ion?
Atoms are the smallest unit of matter that can’t be broken down chemically. Molecules are groups of two or more atoms that are chemically bonded. Ions are atoms or molecules that have gained or lost one or more of their valence electrons and therefore have a net positive or negative charge.
Why do atoms turn into ions?
Ions are formed when atoms lose or gain electrons in order to fulfill the octet rule and have full outer valence electron shells. When they lose electrons, they become positively charged and are named cations. When they gain electrons, they are negatively charged and are named anions.
Can an ion be neutral?
An ion has an imbalance between the number of protons and electrons. In chemistry, the main difference between an atom and an ion is that an atom is a neutral particle, while an ion has a positive or negative electrical charge.
Is an ion always negative?
ion, any atom or group of atoms that bears one or more positive or negative electrical charges. Positively charged ions are called cations ; negatively charged ions, anions, Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms in such a way that both of the electrons of the bond are left in association with one of the formerly bonded atoms.
Examples of these processes include the reaction of a sodium atom with a chlorine atom to form a sodium cation and a chloride anion; the addition of a hydrogen cation to an ammonia molecule to form an ammonium cation; and the dissociation of a water molecule to form a hydrogen cation and a hydroxide anion,
Many crystalline substances are composed of ions held in regular geometric patterns by the attraction of the oppositely charged particles for each other. Ions migrate under the influence of an electrical field and are the conductors of electric current in electrolytic cells. More From Britannica nervous system: The ionic basis of electrical signals The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Adam Augustyn,
Do molecules have an overall charge?
A molecule is usually an electrically neutral group that consists of two or more atoms that are held together by chemical bonds.
Why is the overall charge of an ionic compound neutral?
Answer: – Al will form a cation with a charge of 3+: Al 3+, an aluminum ion. Carbon will form an anion with a charge of 4−: C 4−, a carbide ion. The ions that we have discussed so far are called monatomic ions, that is, they are ions formed from only one atom.
- We also find many polyatomic ions,
- These ions, which act as discrete units, are electrically charged molecules (a group of bonded atoms with an overall charge).
- Some of the more important polyatomic ions are listed in Table 6,
- Oxyanions are polyatomic ions that contain one or more oxygen atoms.
- At this point in your study of chemistry, you should memorize the names, formulas, and charges of the most common polyatomic ions.
Because you will use them repeatedly, they will soon become familiar.
|\text _3\text ^
|\text _3\text ^
|\text _2\text _3
|\text _2\text _4
|\text _2\text _3
|\text _3\text _4
|\text _2\text _4^
|\text _2\text _2\text _4
|\text _2\text _7^
|\text _2\text _2\text _7
|Table 6. Common Polyatomic Ions
Note that there is a system for naming some polyatomic ions; -ate and -ite are suffixes designating polyatomic ions containing more or fewer oxygen atoms. Per- (short for “hyper”) and hypo- (meaning “under”) are prefixes meaning more oxygen atoms than -ate and fewer oxygen atoms than -ite, respectively.
- For example, perchlorate is ClO 4 −, chlorate is ClO 3 −, chlorite is ClO 2 − and hypochlorite is ClO −,
- Unfortunately, the number of oxygen atoms corresponding to a given suffix or prefix is not consistent; for example, nitrate is NO 3 − while sulfate is SO 4 2−,
- This will be covered in more detail in the next module on nomenclature.
The nature of the attractive forces that hold atoms or ions together within a compound is the basis for classifying chemical bonding. When electrons are transferred and ions form, ionic bonds result. Ionic bonds are electrostatic forces of attraction, that is, the attractive forces experienced between objects of opposite electrical charge (in this case, cations and anions).
- When electrons are “shared” and molecules form, covalent bonds result.
- Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms.
- Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them.
When an element composed of atoms that readily lose electrons (a metal) reacts with an element composed of atoms that readily gain electrons (a nonmetal), a transfer of electrons usually occurs, producing ions. The compound formed by this transfer is stabilized by the electrostatic attractions (ionic bonds) between the ions of opposite charge present in the compound.
For example, when each sodium atom in a sample of sodium metal (group 1) gives up one electron to form a sodium cation, Na +, and each chlorine atom in a sample of chlorine gas (group 17) accepts one electron to form a chloride anion, Cl −, the resulting compound, NaCl, is composed of sodium ions and chloride ions in the ratio of one Na + ion for each Cl − ion.
Similarly, each calcium atom (group 2) can give up two electrons and transfer one to each of two chlorine atoms to form CaCl 2, which is composed of Ca 2+ and Cl − ions in the ratio of one Ca 2+ ion to two Cl − ions. A compound that contains ions and is held together by ionic bonds is called an ionic compound,
The periodic table can help us recognize many of the compounds that are ionic: When a metal is combined with one or more nonmetals, the compound is usually ionic. This guideline works well for predicting ionic compound formation for most of the compounds typically encountered in an introductory chemistry course.
However, it is not always true (for example, aluminum chloride, AlCl 3, is not ionic). You can often recognize ionic compounds because of their properties. Ionic compounds are solids that typically melt at high temperatures and boil at even higher temperatures. Figure 3. Sodium chloride melts at 801 °C and conducts electricity when molten. (credit: modification of work by Mark Blaser and Matt Evans) Watch this video to see a mixture of salts melt and conduct electricity. In every ionic compound, the total number of positive charges of the cations equals the total number of negative charges of the anions. Thus, ionic compounds are electrically neutral overall, even though they contain positive and negative ions.