While a certain isotope decays, it emits photons.It is a type of gamma decay.
Isotopes are defined as substances having same number of protons but different number of neutrons.Number of protons is characteristic for determining position of elements in the periodic table.
Since,all isotopes have the same number of protons and hence have same position.They have similar chemical properties as they have same number of electrons.
They find applications in the field of nuclear medicine and oil and gas research . There are 2 types of isotopes : stable and unstable
Unstable isotopes are radioactive and are called as radioisotopes.Some of these isotopes are man -made and hence also called as artificial isotopes.Every element has an isotope which is either man-made or natural .
Many properties of isotopes depend on mass which is measured in atomic mass unit. The difference in actual mass and mass number is called mass defect.
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Answer:
gamma decay.
Explanation:
A gamma decay emits only a gamma-ray photon,
b. solid to gas
c. liquid to gas
d. solid to liquid
Answer:
its D
Explanation:
The element that is most likely to form covalent bonds with carbon (C) is
Selenium (Se)
Explanation
Covalent bond is formed when there is sharing of electrons among two or more non metals.
Both carbon and selenium are non metals therefore they react to form a covalent bond by sharing electron.
Despite krypton been a non metal it does not form a covalent bond with carbon since krypton is inert ( non reactive).
Beryllium (Be) and sodium (Na) are metals therefore they form ionic bond with carbon instead of covalent bond.
Answer: Option (c) is the correct answer.
Explanation:
Atomic number of carbon is 6 and its electronic configuration is 2, 4. So, in order to complete its octet, it requires 4 more electrons.
Therefore, carbon form covalent bonds, that is, it shares electrons with and electron deficient atom.
Krypton is a noble gas and has completely filled octet. So, it will neither give to share its electrons with carbon atom.
Whereas beryllium and sodium does not have enough valence electrons to share. Hence, they will not form bond with carbon atom.
On the other hand, selenium being a non-metal is electron deficient and therefore, in order to complete its octet it will share its electrons with carbon atom.
Thus, we can conclude that the element carbon (C) is most likely to form covalent bonds with the element selenium (Se).
In the second century BCE, the Greek astronomer Ptolemy tried to explain the backward movement of the planets by using a solar system model that included epicycles. For centuries, this was the accepted model. During the Renaissance, Nicholas Copernicus discovered the old heliocentric model of Aristarchus. In Aristarchus’s model, the rising and setting of the Sun was explained by the movement of the Earth.
The heliocentric theory of the Solar System (aka, the heliocentric model) is a theory that places the Sun at the center of the Solar System. It also maintains that the Earth revolves around the Sun.
This theory was first proposed by Nicolaus Copernicus.
Copernicus was the first to propose a theory which differed from Ptolemy's Geocentric System, according to which the earth is at rest in the center with the rest of the planets revolving around it. The claim that all planets revolve around the sun had been raised in ancient times, but Copernicus was the first to succeed in describing the movements of the planets using an astronomical theory which placed the sun at the center.
Therefore, In the second century BCE, the Greek astronomer Ptolemy tried to explain the backward movement of the planets by using a solar system model that included epicycles. For centuries, this was the accepted model. During the Renaissance, Nicholas Copernicus discovered the old heliocentric model of Aristarchus. In Aristarchus’s model, the rising and setting of the Sun was explained by the movement of the Earth.
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Answer:
the first blank is epicycle.
the second blank is Copernicus
the third blank is earth
Answer :
Explanation : We need to simply calculate the division for finding the correct answer and which can be expressed in scientific notation.
The answer on solving will be.
Simple division method was used to find out the answer.
Given data:
Sublimation of K
K(s) ↔ K(g) ΔH(sub) = 89.0 kj/mol
Ionization energy for K
K(s) → K⁺ + e⁻ IE(K) = 419 Kj/mol
Electron affinity for Cl
Cl(g) + e⁻ → Cl⁻ EA(Cl) = -349 kj/mol
Bond energy for Cl₂
1/2Cl₂ (g) → Cl Bond energy = 243/2 = 121.5 kj/mol
Formation of KCl
K(s) + 1/2Cl₂(g) → KCl(s) ΔHf = -436.5 kJ/mol
To determine:
Lattice energy of KCl
K⁺(g) + Cl⁻(g) → KCl (s) U(KCl) = ?
Explanation:
The enthalpy of formation of KCl can be expressed in terms of the sum of all the above processes, i.e.
ΔHf(KCl) = U(KCl) + ΔH(sub) + IE(K) + 1/2 BE(Cl₂) + EA(Cl)
therefore:
U(KCl) = ΔHf(KCl) - [ΔH(sub) + IE(K) + 1/2 BE(Cl₂) + EA(Cl)]
= -436.5 - [89 + 419 + 243/2 -349] = -717 kJ/mol
Ans: the lattice energy of KCl = -717 kj/mol
The lattice energy of KCl is calculated using the Born-Haber cycle by considering the energies of several steps including the sublimation of potassium, ionization of potassium, dissociation of Cl bond, electron affinity of Cl, and formation of KCl. The given values are plugged into a formula resulting in a lattice energy of -718 kJ/mol.
To calculate the lattice energy of KCl using the Born-Haber cycle, we need to follow several thermochemical steps. The steps include, first sublimation of potassium, the ionization of potassium, bond dissociation enthalpy to produce Cl, the electron affinity of Cl, and formation of KCl (s). Combining energy changes associated with all these steps would give us energy change for the formation of KCl from individual K and Cl2, it is called as enthalpy of formation (ΔH°f) for KCl.
Using the given values for each step, we use the formula: ΔH°f = ΔHsub + IE1 + 1/2* DCl2 - EA1 + lattice energy.
Substituting the given values, -436.5 = 89 + 419 + 1/2*243 -349 + lattice energy. Solving gives the lattice energy as -718 kJ/mol.
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Which is a base-conjugate acid pair?
NH3 and CIO3-
NH3 and NH4+
HCIO3 and NH3
HCIO3 and NH4+
The example of base-conjugate acid pair is B. NH3 and NH4+.
A base-conjugate acid pair simply means a pair that consist of two substances that only differ by the presence of a proton (H+).
In this case, the example of base-conjugate acid pair is NH3 and NH4+ because bNH4+ is the conjugate acid of the base NH3.
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Answer:
NH3 and NH4+
Explanation:
NH4+ is the conjugate acid of the base NH3.