Chemistry Unit 1 Summative Review

How do you draw Bohr Models?

To draw Bohr Models, start by placing the element's nucleus at the center, then arrange the electrons in circles, energy levels (n), around the nucleus, with the first circle holding up to 2 electrons (e^-), the second holding up to 8, the third holding up to 18, and the fourth holding up to 32.

What is a periodic trend?

A pattern on the periodic table that happens in a regular interval

What are 3 periodic trends on the table?

Pattern #1: Valence Electrons (increases to the right)

Pattern #2: Atomic Radius (increases to the left and down)

Pattern #3: Reactivity of Metals (increases to the left and down)

What are valence electrons?

Electrons located on the outermost ring of a bohr model.

What are valence shells?

The outermost ring on a bohr model containing electrons.

How do you identify the number of valence electrons an element has just by looking at it on the periodic table?

Each element has a designated amount of valence electrons depending on the group it is in. For example, each element in group 1 on the periodic table has 1 valence electron, group 2 has 2 valence electrons, group 3 has 3 ve^-, and so on.

What is an atomic radius?

The measurement from the nucleus to the valence shell in an atom.

What is coulombic attraction?

The pull of the positive nucleus and the negative electrons in an atom.

How can you determine the atomic radius of an element based on the amount of protons and electrons it has?

The more protons and electrons there are in an element to attract to each other, the smaller the atomic radius of an element is because the strong coulombic attraction contracts the atom, pulling it in and making it smaller. The same is true vice versa (weak coulombic attraction = larger atomic radius)

How many valence electrons do atoms want in order to be stable?

8 valence electrons.

What is effective nuclear charge?

The strength of the nucleus’ pull on the valence electrons.

What are shielding electrons?

Electrons on the shells surrounding an atom’s nucleus, minus the valence shell.

What is the equation for nuclear effective charge?

Z_eff (strength) = Z (total # of protons) - S (shielding electrons)

Who was the Period Table of Elements created by?

Dmitri Mendeleev

Who was the Greek philosopher who named atoms, “atoms”?

Democritus. He originally named them “atomos”, the Greek word for “indivisible” because he had the idea that all matter was made up of tiny, indivisible parts.

What is an element?

A type of atom, organized by atomic number on the periodic table.

Are Alkali Metals and Halogens very reactive, kinda reactive, or not reactive?

Very reactive.

Are Alkaline Earth Metals very reactive, kinda reactive, or not reactive?

Kinda reactive.

Are Noble Gasses very reactive, kinda reactive, or not reactive?

Not reactive.

What is an atom?

The smallest unit of matter, makes up everything.

What are subatomic particles?

“Small things” in an atom. Includes protons, neutrons, and electrons.

Where are protons, neutrons, and electrons located inside an atom?

Protons and neutrons are located in an atom’s nucleus, while electrons are located on an atom’s rings.

What type of charge does a proton have?

Positive charge.

What type of charge does a neutron have?

Neutral charge.

What type of charge does an electron have?

Negative charge.

How much does a proton weigh?

1 amu. (atomic mass unit)

How much does a neutron weigh?

1 amu. (atomic mass unit)

How much does an electron weigh?

0 amu. (atomic mass unit)

What does the atomic number of an element represent?

The number of protons in that element.

What does the number at the bottom of an element represent?

The atomic mass of the element and the total number of protons and neutrons in that element. (M= P + N)

What relationship do protons and electrons have when an atomic element is neutral?

They should be the same.

If an atomic element does have a charge, what equation should you use to find any missing information?

Charge # = P - E

How do you find the neutrons of an atomic element given only its atomic mass and atomic number?

Subtract the atomic number from the atomic mass to get the neutron. (M - P = N)

What role does a proton play in an atom?

It determines the element identity.

What role does a neutron play in an atom?

It stabilizes the nucleus and the whole atom so that the protons (same charge) don’t repel each other and so that the protons and electrons (opposite charges) don’t attract each other, keeping everything in its designated place.

What role does an electron play in an atom?

Electrons participate in chemical reactions.

What are isotopes?

Atoms with the same number of protons but different numbers of neutrons, resulting in a different atomic mass, but keeping the same element.

How do you determine an atomic element’s charge given just the number of protons, neutrons, and electrons?

If there are more protons than electrons, the charge is positive.

If there are more electrons than protons, the charge is negative.

If there number of protons and electrons are the same, the charge is neutral/there is no charge.

What does the atomic mass of a regular element represent vs. the atomic mass of an isotope element?

Atomic mass of a regular element = average mass of every atom under this element

Atomic mass of isotope = mass of 1 specific atom under this element

When finding the neutron or proton of an isotope, do you use the element’s default mass or the given, specific mass?

The given, specific mass.

What is Nuclide Notation (aka Isotope Notation)?

When the atomic number is below the element symbol instead of the top, and the mass is above the element symbol instead of below it.

What is an isotope name?

The name of the element, a dash, and the new given atomic mass. (ex. antimony-121)

When asked to find the valence shell of a specific element, how do you answer?

Answer with the shell/energy level that the valence electrons are found on in a bohr model of that element. For example, for silicon, its valence electrons would be located on the 3rd shell, so you would answer as n = 3.

When ranking elements from smallest to largest or least reactive to most reactive, what should you do?

First, start on the top right hand side of the periodic table, then work your way left and THEN down. If two or more given elements are in the same period, the one on the far right side of the table would be the smallest/least reactive of the two or more. If two or more given elements are in the same group, the one at the top of that group would be the smallest/least reactive, and vice versa.

What causes the atomic radius to increase down a group?

The addition of electron shells to the atom increases the size.

What causes the atomic radius to decrease from left to right across a period?

As more positive charges and negative charges (protons and electrons) are added the same shell, the attraction pulls them closer, shrinking the atomic radius.

What causes metals to become less reactive from left to right across a period?

As you go left to right across a period, the # of protons and electrons increase, causing a stronger Coulombic pull that pulls the valence electrons in closer to the nucleus. Electrons closer to the nucleus are harder for other atoms to steal.

What is the electron shielding effect?

Inner electrons shield the valence electrons from the pull of the nucleus.

How does the effective nuclear charge change left to right across a period? Why?

It increases because the number of protons increase but shielding stays constant.

How does an element's effective nuclear charge affect its reactivity?

If the valence electrons feel a stronger pull from the nucleus then the atom will be less reactive. The electrons will be harder to steal. Therefore, the stronger the effective nuclear charge, the less reactivity the element.