Elements, Compounds, Mixtures

Can an element be broken down into simpler substances?

• Yes

• No

Answer explanation

An element cannot be broken down into simpler substances by chemical methods.

Atom is the smallest unit of an element.

An element is a substance that _______(i)________be broken down into simpler substances by _______(ii)_______ means.

• (i) can, (ii) chemical

• (i) can, (ii) physical

• (i) cannot, (ii) chemical

• (i) cannot, (ii) physical

Tags

NGSS.MS-PS1-1

Each element has a chemical name and a chemical ______.

Elements can be classified as metals and _________________.

Elements can be made up atoms or molecules.

• True

• False

Answer explanation

For example, noble gases, such as helium and neon, are made up of atoms whereas gases such as oxygen (O₂), hydrogen (H₂) and carbon dioxide (CO₂) are made up of molecules.

Tags

NGSS.MS-PS1-1

The chemical symbols for potassium and fluorine are ______ and _____ respectively.

• P and F

• K and F

• Po and F

• Po and Fl

Potassium and fluorine are __________________________.

• both metals

• both non-metals

• non-metal and metal respectively

• metal and non-metal respectively

Answer explanation

Draw the "staircase" in the Periodic Table that divides the metals (on the left) and non-metals (on the right).

What is a compound?

• A compound is a substance made up of one kind of mixture.

• A compound is a substance made up of one kind of element.

• A compound is a substance made up of two or more elements.

A compound is made up of two or more ______________________.

• elements physically mixed.

• elements chemically combined.

Tags

NGSS.MS-PS1-1

A magnesium strip is burnt in air to form magnesium oxide. Which statement is correct?

• Two elements are joined together to form a new mixture.

• Two compounds are joined together to form a new element.

• Two elements are joined together to form a new compound.

• An element and a compound are joined together to form a new compound.

Answer explanation

This is a chemical reaction (combustion). The product formed is a compound as it does not retain the properties of its elements, magnesium and oxygen.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

NGSS.MS-PS1-2