Science STAAR

A Student drew atomic models of four atomic models. Based on the drawings, which one is the least reactive?

• Chlorine, because it has three energy levels with seven electrons in the third level

• Gallium, because it has four energy levels with three electrons in the fourth level

• Neon, because it has two energy levels with eight electrons in the second level

• Tin, because it has five energy levels with four electrons in the fifth level

Tags

NGSS.MS-PS1-1

An atom of which element is represented by this model?

• Carbon (C)

• Neon (Ne)

• Sodium (Na)

• Boron (B)

Tags

NGSS.MS-PS1-1

A student is studying calcium, a highly reactive element that humans need for strong bones. Which characteristic of calcium is most closely related to its chemical reactivity?

• The 20 protons in each atom of calcium

• The 2 valence electrons in each atom of calcium

• The atomic mass of calcium, which is 40.078 amu

• The density of calcium, which is 1.54 g/cm3

An atom consists of 12 protons, 12 electrons, and 12 neutrons. Which of the following can be used to identify the element?

• Neutrons

• Electrons

• Atomic number

• Atomic mass

An atom has 11 protons, 12 neutrons, and 11 electrons. What is the identity of the element?

• Sodium

• Titanium

• Vanadium

• Magnesium

Tags

NGSS.MS-PS1-1

A chemist is identifying the elements present in a sample of seawater. What characteristic of an element’s atoms always determines the element’s identity?

• The number of neutrons

• The number of protons

• The location of valence electrons

• The number of valence electrons

The element Barium (Ba) is made of particles with different atomic charges. Barium has how many neutrons located in it?

• 80 Neutrons

• 81 Neutrons

• 137 Neutrons

• 56 Neutrons

Tags

NGSS.MS-PS1-1

Four students were asked to name the parts of an atom that determine the atom’s identity and chemical properties. The students’ responses are shown in the table below.

• Student 1

• Student 2

• Student 3

• Student 4

Tags

NGSS.MS-PS1-1

How do electrons of an element determine that element's reactivity?

• If the valence shell has missing electrons it is very reactive to attract or lose more electrons.

• If the valence shell has a full ring of electrons it is very reactive because it needs more.

• If the valence shell has a full shell of electrons it is very reactive because it is already full.

• If the valence shell has missing electrons it is not reactive because it is missing electrons.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

How many valence electrons does the atom of Carbon-14, shown above have?

• 14

• 10

• 6

• 4

Tags

NGSS.MS-PS1-1