All categories

3 years ago

Where are elements with similar chemical properties found on the periodic table?

1 answer:

8 0

All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.

You might be interested in

The Valence Electrons of an Atom of Which Element would feel a Greater Effective Nuclear Charge than the Valence?

kumpel [21]

The effective nuclear charge is an innate property of a specific element. It is the pull of force that an electron feels from the nucleus. It is related to the valence electron by the equation: Z* = Z-S, where Z* is the effective nuclear charge, Z is the atomic number and S is the shielding constant.

For the following elements in the choices, these are their values of Z*:

Aluminum - +12.591
Beryllium - +1.912
Hydrogen - +1
Carbon - +4

The effective nuclear charge of Boron is +3. Thus, the answers are Aluminum and Carbon.

5 0

3 years ago

Why does hydrogen have a -1 oxidation state in the compound NaH?

ruslelena [56]

your answer will be :

B. Na has a lower electronegativity than H

because Na belongs to alkali metals which are least electronegative (most electro positive) but hydrogen is a non metal, it has higher electronegativity as compared to metals like Sodium (Na).

6 0

3 years ago

An object's mass is less on the Moon than it is on Earth.

vovikov84 [41]

Answer:

The mass of objects remains constant throughout the universe. This is because an object is made of he same amount of matter (atoms), no matter where you take it in the universe. If you take an object from the Earth to the moon, only the weight will change.

Explanation:

5 0

3 years ago

Which of the following reactions have a positive ΔSrxn? Check all that apply.

PolarNik [594]

Answer:

The reactions that have a positive ΔS rxn are the first and the fourth choices:

2A(g) + B(s) → 3C(g)

2A(g) + 2B(g) → 5C(g)

Explanation:

ΔS rxn is the change of entropy of the chemical reaction.

ΔS rxn = S after reaction - S before reaction.

Therefore, a positive ΔS rxn means that the entropy after the reaction is greater than the entropy before the reaction.

You may use some assumptions to predict whether a reaction will lead an increase or decrease of the entropy.

First, assume that all the non-shown conditions, such as temperature and pressure, are constant.

Under that assumption, and from the meaning of entropy as a measure of the disorder or randomness of a system you can predict the sign of the change of entropy.

2A(g) + B(s) → 3C(g)

1) The solid compounds, B(s) in this case, are very ordered and so they have low entropy.

2) Gas molecules are highly disordered (scattered), and the greater the number of molecules of the gas the larger the entropy, S).

Hence, since the product side shows 3 gas molecules and the reactant side shows 2 gas molecules and 1 solid molecule, you predict that the products have a larger entropy than the reactants, meaning an increase in entropy: ΔS rxn is positive.

2A(g) + B(g) → C(g)

Using the same reasoning, 3 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

A(g) + B(g) → C(g)

Again, 2 gas molecules in the reactant side have more entropy than 1 molecule in the product side, and so the reaction leads to a decrease in the entropy: ΔS rxn is negative

2A(g) + 2B(g) → 5C(g)

With the same reasoing, 5 molecules in the product side, lets you predict that will have more entropy than 4 molecules in the reactant side, and, the entropy will increase: ΔS rxn is positive.

6 0

4 years ago

Compare the polymerisation reaction used to produce poly(ethene) with the

butalik [34]

Answer:

See explanation

Explanation:

Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called a polymer.

There are two kinds of polymers;

-Addition polymers

-Condensation polymers

Addition polymers are formed by the joining of two or more monomers to form a polymer without the elimination of a small molecule.

Condensation polymers are formed by the joining of two or more molecules to form polymers with the elimination of a small molecule.

The main difference between polyethene and polyester is that polyethene is an addition polymer while polyester is a condensation polymer.

In polyethene, ethene molecules are joined together having the repeating unit as [-CH2-CH2-]n.

In polyester, the polymer arises from the reaction of carboxylic acid and an alcohol and loss of water molecules.

5 0

3 years ago