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mihalych1998 [28]
3 years ago
6

Which of the following statements is TRUE? Group of answer choices Elements in the same group have the same number of electron s

hells. Elements in the same period have the same number of valence electrons. Elements in the same group, or family, have similar characteristics, like reactivity and valence electrons. Elements in the same period have similar characteristics, like reactivity and valence electrons.
Chemistry
1 answer:
Gennadij [26K]3 years ago
3 0

Answer:

Elements in the same group, or family, have similar characteristics, like reactivity and valence electrons.  

Explanation:

For example, elements in Group 1 all have one valence electron. They are reactive metals and form ions with a charge of +1.

A is wrong. As you go down a group, each successive atom adds one more valence shell of electrons.

B is wrong. The number of valence electrons changes as you go from left to right across a period.

D is wrong. As you go from left to right across a period, the elements gradually change from metals to metalloids and then to nonmetals.

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Which of the following statements about the atom is false? a. Each atom has a tiny nucleus at its center. b. All the protons and
kvv77 [185]
The false statement is C. According to the Heisenburg uncertainty principle, which inspired the modern 'Electron Cloud' model of the atom, it is nearly impossible to predict an electron's path around the atom. The model statement C is referring to is the Neils Bohr model of the atom, which is useful, but inaccurate.
8 0
4 years ago
The gleaming metallic appearance of the Gateway Arch in St. Louis, Missouri, comes from the stainless steel used in its construc
omeli [17]

Answer:

the mole ratio of chromium to nickel atoms in the steel is 2.383

Explanation:

Given the data in the question;

Chromium  = 19% ( by mass )

Nickel = 9% ( by mass )

now, let the mass of the steel = 100 g

so mass of Chromium  = 19g

mass of nickel = 9g

We know that; Atomic mass of Cr is 52 g/mol, Atomic mass of Ni is 58.7 g/mol

Moles of Cr =  mass/atomic number = 19/52 mol

Moles of Ni =  mass/atomic number = 9/58.7 mol

The mole ratio of of Cr to Ni atom  will be;

⇒ Moles of Cr / Moles of Ni

= (19/52) / (9/58.7)

= 19×58.7 / 9×52

= 2.383

Therefore, the mole ratio of chromium to nickel atoms in the steel is 2.383

8 0
3 years ago
For the reaction 2 HCl + Na2CO3 → 2 NaCl + H2O + CO2 8.0 moles of CO2 is collected at STP. What is the volume of CO2? 1. 57.6 L
Dmitry [639]

Answer:

Option 5. 179L

Explanation:

The reaction is:

2 HCl + Na₂CO₃ → 2NaCl + H₂O + CO₂

The amount of collected CO₂ is 8 moles.

We apply the Ideal Gases Law at STP

STP are 1 atm of pressure and 273K of T°

P . V = n . R . T

1atm . V = 8 mol .0.082L.atm/mol.K . 273K

V = (8 mol .0.082L.atm/mol.K . 273K) / 1 atm = 179 L

6 0
4 years ago
What does the roman numeral stand for in copper(1) oxide should it not be copper(II) oxide
photoshop1234 [79]

Answer:

The roman numeral in copper(I) oxide indicates that the oxidation number of copper in the compound is 1.

Explanation:

Roman numeral is used to indicate the oxidation number of an element in a compound.

The roman numeral in copper(I) oxide indicates that the oxidation number of copper in the compound is 1.

This can be seen from the following illustration:

copper(I) oxide => Cu₂O

Oxidation number of O = –2

Oxidation number of Cu₂O = 0

Oxidation number of Cu =?

Cu₂O = 0

2Cu + O = 0

2Cu – 2 = 0

Collect like terms

2Cu = 0 + 2

2Cu = 2

Divide both side by 2

Cu = 2/2

Cu = 1

Thus, we can see that the oxidation number of Cu in Cu₂O is 1. Hence the name of Cu₂O is copper(I) oxide indicating that the oxidation number of of copper (Cu) in the compound is 1.

For copper(II) oxide, we shall determine the oxidation number of Cu. This can be obtained as follow:

copper(II) oxide, CuO => CuO

Oxidation number of O = –2

Oxidation number of CuO = 0

Oxidation number of Cu =?

CuO = 0

Cu + O = 0

Cu – 2 = 0

Collect like terms

Cu = 0 + 2

Cu = 2

Thus, the oxidation number of Cu in CuO is 2. Hence the name of CuO is copper(II) oxide indicating that the oxidation number of of copper (Cu) in the compound is 2.

From the above illustrations,

We can see that the roman numeral in both copper(I) oxide, Cu₂O and copper(II) oxide, CuO are different because the oxidation number of Cu in both cases are different.

3 0
3 years ago
A student placed 19.0 g of glucose (c6h12o6) in a volumetric flask, added enough water to dissolve the glucose by swirling, then
EleoNora [17]
  <span>moles glucose = 19 g / 180 g/mol= 0.105 
M = 0.105 / 0.100 L = 1.05 

moles in 20.0 mL = 1.05 M x 0.0200 L = 0.0216 

New concentration = 0.0216 /0.500 L = 0.0432 M 
moles in 100 mL = 0.100 L x 0.0432 = 0.00432 

mass = 0.00432 x 180 g/mol= 0.778 g</span>
7 0
3 years ago
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