The Periodic Table

In the modern periodic table, what are the vertical columns of elements called?

Groups.

In the modern periodic table, what are the horizontal rows of elements called?

Periods.

Elements are arranged in the modern periodic table in order of increasing _____ _____.

atomic number

What do elements in the same group of the periodic table have in common regarding their electron structure?

They have the same number of electrons in their outer shell.

What do elements in the same period of the periodic table have in common regarding their electron structure?

They have the same number of electron shells.

Why is the periodic table so named?

Because elements with similar properties occur at regular intervals.

Who created an early version of the periodic table in 1869, arranging elements by atomic weight and leaving gaps for undiscovered elements?

Dmitri Mendeleev.

Mendeleev overcame issues in his periodic table by leaving _____ for elements he predicted were not yet discovered.

gaps

Why did Mendeleev swap the positions of iodine and tellurium in his periodic table, despite tellurium having a higher atomic weight?

To make iodine line up with other elements that had similar chemical properties (chlorine and bromine).

The existence of what atomic feature explains the 'pair reversals' (like iodine and tellurium) in Mendeleev's atomic weight-based table?

Isotopes.

John Newlands arranged elements in order of atomic weight and noticed similar properties occurred every eighth element, which he called the 'law of _____'.

octaves

Where are metals generally found on the periodic table?

On the left of the stepped line and towards the bottom.

Where are non-metals generally found on the periodic table?

On the right of the stepped line and towards the top.

What type of ions do metal atoms typically form when they react?

Positive ions (by losing electrons).

What type of ions do non-metal atoms typically form when they react?

Negative ions (by gaining electrons).

What is the name for the elements in Group 0 of the periodic table?

The noble gases.

Why are the noble gases (Group 0) unreactive or inert?

They have a full outer shell of electrons, which is a stable arrangement.

What is the trend in boiling points for the noble gases as you go down Group 0?

The boiling points increase.

Why do the boiling points of noble gases increase down the group?

The atoms become larger, leading to stronger intermolecular forces that require more energy to overcome.

What is the name for the elements in Group 1 of the periodic table?

The alkali metals.

How many electrons do Group 1 elements have in their outer shell?

One.

Describe three physical properties typical of alkali metals.

They are soft, have low densities, and have relatively low melting points.

What is the trend in melting points for the alkali metals as you go down Group 1?

The melting points decrease.

What is the trend in reactivity for the alkali metals as you go down Group 1?

The reactivity increases.

Why does reactivity increase as you go down Group 1?

The outer electron is further from the nucleus, attraction decreases, and it is lost more easily.

What are the two products formed when an alkali metal reacts with water?

A metal hydroxide and hydrogen gas.

What observation indicates that an alkaline solution is formed when a Group 1 metal reacts with water?

Universal indicator turns blue or purple.

Describe the observation when potassium is added to water.

It burns violently with a lilac flame, melts into a ball, and disappears rapidly, often with a small explosion.

What is the product when a Group 1 metal reacts with chlorine?

A metal chloride (a white solid).

Write the balanced chemical equation for the reaction of sodium with chlorine.

2Na (s) + Cl₂ (g) → 2NaCl (s)

What is formed when an alkali metal reacts with oxygen?

A metal oxide.

What is the name for the elements in Group 7 of the periodic table?

The halogens.

How many electrons do Group 7 elements have in their outer shell?

Seven.

Halogen elements exist as _____ molecules, where atoms are joined in pairs.

diatomic

What is the state of chlorine at room temperature?

A pale green gas.

What is the state of bromine at room temperature?

A brown liquid.

What is the state of iodine at room temperature?

A purple-black solid.

What is the trend in melting and boiling points for the halogens as you go down Group 7?

The melting and boiling points increase.

Why do the melting and boiling points of halogens increase down the group?

The molecules become larger, leading to stronger intermolecular forces that require more energy to overcome.

What is the trend in reactivity for the halogens as you go down Group 7?

The reactivity decreases.

Why does reactivity decrease as you go down Group 7?

The outer shell is further from the nucleus, making it harder for the atom to gain an electron due to decreased attraction and increased shielding.

When a halogen reacts with a metal, what type of compound is formed?

An ionic compound (a salt).

When a halogen atom gains an electron to form a 1- ion, it is called a _____.

halide

What is a displacement reaction in the context of halogens?

A reaction where a more reactive halogen displaces a less reactive halogen from an aqueous solution of its salt.

Complete the word equation: chlorine + potassium iodide → ?

potassium chloride + iodine

Would bromine displace chlorine from a solution of sodium chloride? Explain why.

No, because bromine is less reactive than chlorine.

Where are the transition elements located in the periodic table?

In the central block, between Group 2 and Group 3.

Compared to Group 1 metals, transition metals are generally harder, stronger, and have higher _____.

densities

Compared to alkali metals, what is a key difference in the melting points of most transition metals?

They have higher melting points.

How does the reactivity of transition metals generally compare to that of Group 1 metals?

They are much less reactive.

A key chemical property of transition elements is that they can form ions with _____ charges.

different (or multiple)

What is a characteristic property of the compounds formed by transition elements?

They are often coloured.

Transition metals are often useful as _____, which are substances that increase the rate of a reaction without being used up.

catalysts

Which transition metal is used as a catalyst in the Haber process for making ammonia?

Iron (Fe).

Most metal oxides are described as chemically _____.

basic

Most non-metal oxides are described as chemically _____.

acidic

The ability of a metal to be bent or hammered into shape without snapping is called _____.

malleability

A non-metal, when solid, is typically _____, meaning it breaks easily.

brittle

When halogens react with other non-metals, such as hydrogen, they form _____ compounds.

covalent

What is the name of the compound formed when hydrogen reacts with chlorine?

Hydrogen chloride (HCl).

What is formed when a hydrogen halide gas, like HCl (g), dissolves in water?

An acidic solution (e.g., hydrochloric acid).