question 1
what is the most common ionic charge of an atom of astatine?
question 2
what is the order from lowest to highest ionization energy of these three elements: potassium, calcium, and chlorine?
question 3
consider the following ions: sn⁺², sb⁺³, te⁻¹, rb⁺¹, i⁻¹, ag
what pair of ions are isoelectronic with each other?
question 4
when sodium bonds with oxygen, how many sodium atoms and oxygen atoms are needed to complete the ionic bond?
question 5
what type of bond is formed between sulfur and oxygen?
question 6
what type of bond is formed between calcium and chlorine?
question 7
which types of covalent bonds are present in a molecule of nitrogen dioxide (no₂)?
question 8
how many dots (nonbonding electrons) appear in the final lewis structure of phosphine (ph₃)?

Question

Accepted Answer

Let's solve these chemistry (Natural Science - Chemistry) problems one by one:

### Question 1: Most common ionic charge of astatine
Astatine (At) is a halogen (Group 17). Halogens typically gain 1 electron to achieve a stable octet, so they have a -1 ionic charge.
# Brief Explanations:
Astatine is in Group 17 (halogens). Halogens gain 1 electron to form stable ions, so the common ionic charge is -1.
# Answer:
-1

### Question 2: Ionization energy order (K, Ca, Cl)
Ionization energy generally increases across a period (left to right) and decreases down a group. Potassium (K) is in Period 4, Group 1; Calcium (Ca) is in Period 4, Group 2; Chlorine (Cl) is in Period 3, Group 17.
- K is in Group 1, has low ionization energy (loses electron easily).
- Ca is in Group 2, higher than K (needs more energy to remove electron than K).
- Cl is in Period 3 (higher effective nuclear charge than Period 4 elements) and Group 17, so highest ionization energy.
Order: K < Ca < Cl
# Brief Explanations:
Ionization energy increases across a period (left - right) and decreases down a group. K (Group 1, Period 4), Ca (Group 2, Period 4), Cl (Group 17, Period 3). So order from lowest to highest: K < Ca < Cl.
# Answer:
Potassium < Calcium < Chlorine (or K < Ca < Cl)

### Question 3: Isoelectronic ions (Sn²⁺, Sb³⁺, Te⁻, Rb⁺, I⁻, Ag)
Isoelectronic species have the same number of electrons.
- Sn (atomic number 50), Sn²⁺: 50 - 2 = 48 electrons.
- Sb (atomic number 51), Sb³⁺: 51 - 3 = 48 electrons.
- Te (atomic number 52), Te⁻: 52 + 1 = 53 electrons.
- Rb (atomic number 37), Rb⁺: 37 - 1 = 36 electrons.
- I (atomic number 53), I⁻: 53 + 1 = 54 electrons.
- Ag (atomic number 47), Ag: 47 electrons.

So Sn²⁺ and Sb³⁺ have 48 electrons (isoelectronic).
# Brief Explanations:
Isoelectronic ions have the same electron count. Calculate electrons for each: Sn²⁺ (50 - 2 = 48), Sb³⁺ (51 - 3 = 48), so they are isoelectronic.
# Answer:
Sn²⁺ and Sb³⁺

### Question 4: Sodium - Oxygen ionic bond
Sodium (Na) has a +1 charge (Na⁺), Oxygen (O) has a -2 charge (O²⁻). To balance charges: 2 Na⁺ (total +2) and 1 O²⁻ (total -2). So 2 sodium atoms and 1 oxygen atom.
# Brief Explanations:
Na⁺ (charge +1), O²⁻ (charge -2). Use charge balance: 2*(+1) + 1*(-2) = 0. So 2 Na atoms and 1 O atom.
# Answer:
2 sodium atoms and 1 oxygen atom

### Question 5: Bond between sulfur and oxygen
Sulfur (S) and Oxygen (O) are both non - metals. Non - metals form covalent bonds (share electrons) with each other.
# Brief Explanations:
S and O are non - metals. Non - metals share electrons, so they form a covalent bond.
# Answer:
Covalent bond

### Question 6: Bond between calcium and chlorine
Calcium (Ca) is a metal (Group 2, forms Ca²⁺), Chlorine (Cl) is a non - metal (Group 17, forms Cl⁻). Metals and non - metals transfer electrons, forming ionic bonds.
# Brief Explanations:
Ca (metal, forms Ca²⁺) and Cl (non - metal, forms Cl⁻). Metal - non - metal bond is ionic (electron transfer).
# Answer:
Ionic bond

### Question 7: Covalent bonds in NO₂
Nitrogen (N) has 5 valence electrons, Oxygen (O) has 6. In NO₂, N is the central atom. The Lewis structure has a double bond (2 shared pairs) and a single bond (1 shared pair) or resonance structures with one double and one single bond (but in terms of bond types: one sigma (σ) and one pi (π) in the double bond, and one sigma (σ) in the single bond? Wait, more accurately, NO₂ has a total of three covalent bonds (resonance - but the bond types: there are two bonds between N and O, one is a double bond (consists of 1 σ and 1 π bond) and one is a single bond (1 σ bond), but overall, the bonds are one double (with σ and π) and one single (σ), but the types of covalent bonds present are sigma (σ) and pi (π) bonds. Wait, the question is "which types of covalent bonds" - in NO₂, there is a double bond (containing 1 σ and 1 π) and a single bond (1 σ), but the bond types are sigma (σ) and pi (π) bonds. Alternatively, considering the actual bonding: NO₂ has a total of three bonding electrons? Wait, no. Let's re - calculate valence electrons: N (5) + 2*O(6) = 5 + 12 = 17. Wait, odd number. The Lewis structure: N is central, bonded to two O atoms. One O is double - bonded (2 shared pairs), one O is single - bonded (1 shared pair), and N has one unpaired electron. So the bonds: one double bond (σ and π) and one single bond (σ). So the types of covalent bonds are sigma (σ) and pi (π) bonds.
# Brief Explanations:
In NO₂, the bonds between N and O include a double bond (with 1 σ and 1 π bond) and a single bond (1 σ bond). So the covalent bond types present are sigma (σ) and pi (π) bonds.
# Answer:
Sigma (σ) and pi (π) bonds (or one double bond (with σ and π) and one single bond (σ), but the types are σ and π)

### Question 8: Non - bonding electrons in PH₃ Lewis structure
Phosphorus (P) has 5 valence electrons. It bonds with 3 H atoms (each H has 1 valence electron). In PH₃, P forms 3 single bonds with H (sharing 3 electrons, so 3*2 = 6 electrons in bonds). P has 5 - 3 = 2 non - bonding electrons? Wait, no: Valence electrons of P: 5. Each H contributes 1, so total valence electrons: 5+3*1 = 8. In Lewis structure, P is central, bonded to 3 H (3 single bonds: 3*2 = 6 electrons). So non - bonding electrons on P: 8 - 6 = 2? Wait, no, 5 (P's valence) - 3 (bonds, each bond uses 1 of P's electrons) = 2? Wait, no, the formula for non - bonding electrons (lone pairs) on central atom: For PH₃, the Lewis structure is P with 3 single bonds to H, and one lone pair? Wait, no: 5 valence electrons of P. 3 bonds (each bond is a pair, so 3*2 = 6 electrons, but P contributes 1 electron per bond, so 3 electrons from P, and 3 from H). So P has 5 - 3 = 2 electrons left? No, that's wrong. Wait, total valence electrons: 5 (P) + 3*1 (H) = 8. The Lewis structure: P is in the center, bonded to 3 H atoms (3 single bonds: each bond is 2 electrons, so 6 electrons in bonds). Then the remaining electrons: 8 - 6 = 2? But that would be 1 lone pair (2 electrons). Wait, no, P has 5 valence electrons. When it forms 3 bonds (each bond is a shared pair), it uses 3 electrons, so it has 5 - 3 = 2 electrons left, which is 1 lone pair (2 electrons). Wait, but actually, in PH₃, the Lewis structure has P with 3 single bonds to H and one lone pair (2 non - bonding electrons). Wait, no, 5 valence electrons: 3 bonds (each bond is a pair, so 3*2 = 6 electrons, but P provides 1 electron for each bond, so 3 electrons from P, and H provides 3. So P has 5 - 3 = 2 electrons left, which is 1 lone pair (2 electrons). So the number of non - bonding electrons (dots) is 2? Wait, no, wait: the Lewis structure of PH₃: P is bonded to 3 H, and has one lone pair (2 electrons). So the number of non - bonding electrons (dots) is 2? Wait, no, let's count again. Valence electrons: P (5) + 3H (3) = 8. The structure: P - H, P - H, P - H. Each bond is 2 electrons, so 3 bonds * 2 = 6 electrons. Remaining electrons: 8 - 6 = 2, which are on P as a lone pair (2 electrons, so 1 pair, 2 dots? Wait, no, a lone pair is 2 electrons, so 2 dots? Wait, no, in Lewis structure, we represent lone pairs as pairs of dots. So P has one lone pair (2 electrons), so 2 dots? Wait, no, 5 valence electrons: 3 used in bonding (each bond is a single bond, so 3 electrons from P), so 5 - 3 = 2 electrons left, which is 1 lone pair (2 electrons). So the number of non - bonding electrons (dots) is 2? Wait, no, I think I made a mistake. Wait, P has 5 valence electrons. When it forms 3 single bonds with H, each bond is a shared pair (so P contributes 1 electron to each bond, H contributes 1). So total electrons around P: 3*2 (from bonds) + 2 (lone pair) = 8, which is correct (octet for P? Wait, P is in Period 3, can have expanded octet, but in PH₃, it follows octet. Wait, 3 bonds (6 electrons) + 2 lone pair electrons = 8, which is octet. So the number of non - bonding electrons (dots) is 2? Wait, no, a lone pair is 2 electrons, so in Lewis structure, we draw two dots (a pair) on P. So the number of non - bonding electrons (dots) is 2? Wait, no, let's check a reference. The Lewis structure of PH₃: P is bonded to 3 H, and has one lone pair (2 electrons). So the number of non - bonding electrons (dots) is 2? Wait, no, 5 valence electrons: 3 in bonds, 2 in lone pair. So 2 non - bonding electrons (1 lone pair, 2 dots).
# Brief Explanations:
Valence electrons of P: 5. PH₃ has 3 P - H bonds (6 bonding electrons). Remaining electrons: 5 - 3 (bonds, 1 electron per bond from P) = 2? Wait, total valence electrons: 5+3 = 8. Bonding electrons: 6 (3 bonds). Non - bonding electrons: 8 - 6 = 2. So 2 non - bonding electrons (dots) on P.
# Answer:
2

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Question 1: Most common ionic charge of astatine

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Question 2: Ionization energy order (K, Ca, Cl)